@echo off
rem 假设待处理的txt文件位于C:\test文件夹下
cd /d "C:\test"
for /f "delims=" %%a in ('dir /s /b "*.txt"') do (
    type nul >"%%~na.new"
    for /f "usebackq delims=" %%h in ("%%a") do (
        >>"%%~na.new" echo,%%h,%%~na
    )
)
for %%a in (*.new) do (
    move "%%a" "%%~na.txt"
)