diff --git a/doc/reference-README.md b/doc/reference-README.md
index 6a18768..8505009 100644
--- a/doc/reference-README.md
+++ b/doc/reference-README.md
@@ -51,7 +51,7 @@ cat /test/funcrparams.sysy
 
 - 参照SysY语言规范，修改`src/SysY.g4`文件，实现SysY词法/语法的完整定义
 - 修改任意代码后需要重新执行`cmake --build build`命令重新构建项目，ANTLR工具会从`SysY.g4`生成词法/语法分析器，生成的文件位于`./build/src`目录
-- （进阶内容）修改`src/ASTPrinter.h`与`src/ASTPrinter.cpp`，实现从AST输出源程序，但输出的源程序是经过格式化的，测试用例为`test/format-test.sy`，格式化后的参考结果为`test/format-ref.sy`
+- （进阶内容）修改`src/ASTPrinter.h`与`src/ASTPrinter.cpp`，实现从AST输出源程序，但输出的源程序是经过格式化的
 
 ## 实验2：生成中间表示
 
diff --git a/src/frontend/SyntaxTreePrinter.cpp b/src/frontend/SyntaxTreePrinter.cpp
index 0593105..1ec0cab 100644
--- a/src/frontend/SyntaxTreePrinter.cpp
+++ b/src/frontend/SyntaxTreePrinter.cpp
@@ -1,9 +1,6 @@
 #include "frontend/SyntaxTreePrinter.h"
 
 #include <string>
-#include <vector>
-
-#include "SysYParser.h"
 
 namespace {
 
@@ -23,104 +20,8 @@ std::string GetTokenName(const antlr4::Token* tok, antlr4::Parser* parser) {
   return token_name;
 }
 
-bool KeepImportantToken(const std::string& token_name) {
-  return token_name == "Ident" || token_name == "Number" ||
-         token_name == "Assign" || token_name == "AddOp";
-}
-
-std::string PrettyPrimary(SysYParser::PrimaryContext* primary) {
-  if (!primary) {
-    return "";
-  }
-  if (primary->Number()) {
-    return primary->Number()->getText();
-  }
-  if (primary->Ident()) {
-    return primary->Ident()->getText();
-  }
-  if (primary->exp()) {
-    return "(" + primary->exp()->getText() + ")";
-  }
-  return primary->getText();
-}
-
-std::string PrettyAddExp(SysYParser::AddExpContext* add_exp) {
-  if (!add_exp) {
-    return "";
-  }
-  const auto terms = add_exp->primary();
-  if (terms.empty()) {
-    return "";
-  }
-  std::string out = PrettyPrimary(terms[0]);
-  for (size_t i = 1; i < terms.size(); ++i) {
-    out += " + " + PrettyPrimary(terms[i]);
-  }
-  return out;
-}
-
-std::string PrettyExp(SysYParser::ExpContext* exp) {
-  if (!exp || !exp->addExp()) {
-    return "";
-  }
-  return PrettyAddExp(exp->addExp());
-}
-
-std::string PrettyRuleText(antlr4::ParserRuleContext* rule) {
-  if (!rule) {
-    return "";
-  }
-  if (auto* var_decl = dynamic_cast<SysYParser::VarDeclContext*>(rule)) {
-    std::string out = "int " + var_decl->Ident()->getText();
-    if (var_decl->exp()) {
-      out += " = " + PrettyExp(var_decl->exp());
-    }
-    out += ";";
-    return out;
-  }
-  if (auto* ret = dynamic_cast<SysYParser::ReturnStmtContext*>(rule)) {
-    return "return " + PrettyExp(ret->exp()) + ";";
-  }
-  if (dynamic_cast<SysYParser::FuncDefContext*>(rule) != nullptr) {
-    return "int main()";
-  }
-  if (auto* stmt = dynamic_cast<SysYParser::StmtContext*>(rule)) {
-    if (stmt->varDecl()) {
-      return PrettyRuleText(stmt->varDecl());
-    }
-    if (stmt->returnStmt()) {
-      return PrettyRuleText(stmt->returnStmt());
-    }
-  }
-  if (auto* exp = dynamic_cast<SysYParser::ExpContext*>(rule)) {
-    return PrettyExp(exp);
-  }
-  if (auto* add_exp = dynamic_cast<SysYParser::AddExpContext*>(rule)) {
-    return PrettyAddExp(add_exp);
-  }
-  if (auto* primary = dynamic_cast<SysYParser::PrimaryContext*>(rule)) {
-    return PrettyPrimary(primary);
-  }
-  return "";
-}
-
-bool HasVisibleNode(antlr4::tree::ParseTree* node, antlr4::Parser* parser) {
-  auto* terminal = dynamic_cast<antlr4::tree::TerminalNode*>(node);
-  if (terminal) {
-    const std::string token_name = GetTokenName(terminal->getSymbol(), parser);
-    return KeepImportantToken(token_name);
-  }
-  for (auto* child : node->children) {
-    if (HasVisibleNode(child, parser)) {
-      return true;
-    }
-  }
-  return false;
-}
-
-std::string RuleName(antlr4::tree::ParseTree* node, antlr4::Parser* parser) {
-  auto* rule = dynamic_cast<antlr4::ParserRuleContext*>(node);
-  if (!parser || !rule) {
+std::string RuleName(antlr4::ParserRuleContext* rule, antlr4::Parser* parser) {
+  if (!rule || !parser) {
     return "unknown";
   }
   const int idx = rule->getRuleIndex();
@@ -131,47 +32,34 @@ std::string RuleName(antlr4::tree::ParseTree* node, antlr4::Parser* parser) {
   return "unknown";
 }
 
-std::string NodeLabel(antlr4::tree::ParseTree* node, antlr4::Parser* parser) {
-  auto* terminal = dynamic_cast<antlr4::tree::TerminalNode*>(node);
-  if (terminal) {
-    return GetTokenName(terminal->getSymbol(), parser) + ": " + node->getText();
-  }
-
-  const std::string rule_name = RuleName(node, parser);
-  auto* rule = dynamic_cast<antlr4::ParserRuleContext*>(node);
-  const std::string pretty = PrettyRuleText(rule);
-  if (!pretty.empty()) {
-    return rule_name + " (" + pretty + ")";
-  }
-  return rule_name;
-}
-
 void PrintSyntaxTreeImpl(antlr4::tree::ParseTree* node, antlr4::Parser* parser,
                          std::ostream& os, const std::string& prefix,
                          bool is_last, bool is_root) {
-  if (!HasVisibleNode(node, parser)) {
+  if (!node) {
     return;
   }
 
-  if (is_root) {
-    os << NodeLabel(node, parser) << "\n";
+  std::string label;
+  if (auto* terminal = dynamic_cast<antlr4::tree::TerminalNode*>(node)) {
+    label = GetTokenName(terminal->getSymbol(), parser) + ": " + terminal->getText();
+  } else if (auto* rule = dynamic_cast<antlr4::ParserRuleContext*>(node)) {
+    label = RuleName(rule, parser);
   } else {
-    os << prefix << (is_last ? "└── " : "├── ") << NodeLabel(node, parser)
-       << "\n";
+    label = "unknown";
   }
 
-  std::vector<antlr4::tree::ParseTree*> children;
-  for (auto* child : node->children) {
-    if (HasVisibleNode(child, parser)) {
-      children.push_back(child);
-    }
+  if (is_root) {
+    os << label << "\n";
+  } else {
+    os << prefix << (is_last ? "`-- " : "|-- ") << label << "\n";
   }
 
   const std::string child_prefix =
-      is_root ? "" : prefix + (is_last ? "    " : "│   ");
-  for (size_t i = 0; i < children.size(); ++i) {
-    PrintSyntaxTreeImpl(children[i], parser, os, child_prefix,
-                        i + 1 == children.size(), false);
+      is_root ? "" : prefix + (is_last ? "    " : "|   ");
+  const size_t child_count = node->children.size();
+  for (size_t i = 0; i < child_count; ++i) {
+    PrintSyntaxTreeImpl(node->children[i], parser, os, child_prefix,
+                        i + 1 == child_count, false);
   }
 }
 
diff --git a/src/frontend/SyntaxTreePrinter.h b/src/frontend/SyntaxTreePrinter.h
index 5dd6265..4633b5e 100644
--- a/src/frontend/SyntaxTreePrinter.h
+++ b/src/frontend/SyntaxTreePrinter.h
@@ -4,6 +4,6 @@
 
 #include "antlr4-runtime.h"
 
-// 以树状缩进形式打印语法树（仅保留关键节点/记号）。
+// 以树状缩进形式直接打印 ANTLR parse tree。
 void PrintSyntaxTree(antlr4::tree::ParseTree* tree, antlr4::Parser* parser,
                      std::ostream& os);