Did you skip step 1? https://github.com/OpenModelica/OpenMod … v-MINGW.md

OMDev is where you installed it. Clone https://openmodelica.org/git/OMDev.git into C:\OMDev and set the OMDev environment variable to that location and you should get further.

yes , i do install OMDev ,  the path is C:\OMDev and I config system virable . mingw32.exe is not in  C:\OMDev\tools\msys\mingw32 .

just now, i download OpenModelicaEclipseWorkspace.zip    form https://www.openmodelica.org/documents/ , it dose not work .

i fund the config is wrong,  for example ,OMDev-MINGW-OpenModelicaBuilder -> Main ,  OMDev\tools\msys\bin\ not have make.exe

i hope more detail doc !

thank you

OMDev repository is  C:\OMDev from https://openmodelica.org/svn/OpenModeli … dows/OMDev

Note that OMDev repository from the SVN is old, you need the new one form GIT: https://openmodelica.org/git/OMDev.git

Read here how to clone the repository:
https://github.com/OpenModelica/OpenMod … v-MINGW.md

I follow your tips,  set  environment in eclipse, when i press ctrl + B， eclipse pop a  input window says "please input  a value" .  i hava no idea what to input.

There you can give targets to make or variables to consider when building. Just leave it empty (press Enter) if you just want to build the OpenModelica compiler (omc).
If you have more CPU cores, write -jNumberOfCores, so if you have 4 write -j4. The compilation will be faster if you have more cores. Write omedit in there if you want to build OMEdit.