Comparative study of the coseismic effects of well water level and well water temperature at the Gansu seismic stations finds that there are many obvious differences between the Wenchuan MS8. 0 earthquake in 2008 and the Japan MS9. 0 earthquake in 2009． The majority of well water level and well water temperature recorded the coseismic effect after Wenchuan earthquake with larger magnitude and longer duration． Despite the release of larger energy by the Janpan earthquake，only a few well water level recorded the coseismic change with little change in well water temperature，which were affected by the epicentral distance and focal orientation，Well water level in Gulang station recorded the change after the two earthquakes，with a larger magnitude after Japan earthquake than after the Wenchuan earthquake． The phenomenon is worthy of further study．