Hello123World

@echo off
cd.>2.txt
setlocal enabledelayedexpansion
for /f "tokens=*" %%i in (1.txt) do (
set var=%%i
set "var=!var:system32\drivers\=C:\WINDOWS\system32\drivers\!" 
echo !var!>>2.txt 
) 
pause>nul
复制代码

你的代码多了个%，所以导致出错。

Hello123World

(for /f "tokens=*" %%i in (1.txt) do (echo %windir%\%%i))>2.txt 
复制代码

也行