Hello Ying Yan,
A few things that may help if you haven't figured this out already.
1. If the EPLaunch version doesn't match the IDF file version, there is usually a warning saying so.
2. There is a "Version" object in your IDF file. If that doesn't match, you will usually get this warning.
3. You can try to trick the program into getting rid of this warning by just changing the version in the IDF file in a text editor, but this is merely cosmetic.
4. If you know your IDF version is 8.0 or the latest version, I would just download and install the latest version of EnergyPlus, then they should match.