正如我看到你使用“老式”代码。我认为微软已经打破了“WIN.INI”的功能-文件直接从Win 9 X交付。尝试使用通用的WinApi解决方案。这应该有帮助：https://learn.microsoft.com/en-us/windows/win32/printdocs/setdefaultprinter

谢谢，这段代码对我有用：

procedure TForm1.SetDefaultPrinter(Name: string);
  var
    fnSetDefaultPrinter: function(pszPrinter: PChar): Bool; stdcall;
    H: THandle;
    Size, Dummy: Cardinal;
    PrinterInfo: PPrinterInfo2;
begin
   if (Win32Platform = VER_PLATFORM_WIN32_NT) and (Win32MajorVersion >= 5) then begin
     @fnSetDefaultPrinter := GetProcAddress(GetModuleHandle(winspl), 'SetDefaultPrinterW');
     if (@fnSetDefaultPrinter = NIL) then
       RaiseLastOSError;
     if NOT fnSetDefaultPrinter(PChar(Name)) then
       RaiseLastOSError;
   end
   else begin
     if NOT OpenPrinter(PChar(Name), H, NIL) then
       RaiseLastOSError;
     try
       GetPrinter(H, 2, NIL, 0, @Size);
       if GetLastError <> ERROR_INSUFFICIENT_BUFFER then
         RaiseLastOSError;
       GetMem(PrinterInfo, Size);
       try
         if NOT GetPrinter(H, 2, PrinterInfo, Size, @Dummy) then
           RaiseLastOSError;
         PrinterInfo^.Attributes := PrinterInfo^.Attributes or PRINTER_ATTRIBUTE_DEFAULT;
         if NOT Winspool.SetPrinter(H, 2, PrinterInfo, PRINTER_CONTROL_SET_STATUS) then
           RaiseLastOSError;
       finally
         FreeMem(PrinterInfo);
       end;
     finally
       ClosePrinter(H);
     end;
   end;
end;