1．调用API函数 
procedure CopyFile(FromFileName,ToFileName:string);
var
f1,f2:file;
Begin
AssignFile(f1,FromFileName); file://指定源文件名
AssignFile(f2,ToFileName); file://指定目标文件名
Reset(f1);
Try
Rewrite(f2);
Try
If Lzcopy(TfileRec(f1).handle,TfileRec(f2).Handle)<0
Then
Raise EinoutError.creat('文件复制错误')
Finally
CloseFile(f2); file://关闭 f2
End;
Finally
Until length(sLine)<=0;
End;
End;

2.文件流

procedure copyfile;
var f1,f2: tfilestream ;
begin
f1:=Tfilestream.Create(sourcefilename,fmopenread);
try
f2:=Tfilestream.Create(targetfilename,fmopenwrite or fmcreate);
try
f2.CopyFrom(f1,f1.size);
finally
f2.Free;
end;
finally
f1.Free;
end;
end; 
3．利用内存块读写buffer实现

Procudure FileCopy(const Fromfile,Tofile:string);
Var
F1,F2:file;
NumRead,Numwritten:word;
Buf:array [1..2048] of char;
Begin
AssignFile(F1,Fromfile);
Reset(F1,1);
AssignFile(F2,Tofile);
Rewrite(F2,1);
Repeat
BlockRead(F1,buf,sizeof(buf),NumRead);
BlockWrite(F2,buf,Numread,NumWritten);
Until (NumRead=0) or (NumWritten<>NumRead);
CloseFile(F1);
CloseFile(F2);
End;