echo %date:~0,4%%date:~5,2%%date:~8,2%

输出：20170315

echo %date:~0,4%-%date:~5,2%-%date:~8,2%

输出：2017-03-15

对小时，不够两位需要格式化

@echo off

set hour=%time:~,2%

if "%time:~,1%"==" " set hour=0%time:~1,1%

echo %date:~0,4%%date:~5,2%%date:~8,2%%hour%%time:~3,2%%time:~6,2%

pause