Abstract: Coseismic groundwater level changes of strong earthquakes (with Ms≥6 in china and Ms≥7 out of china) recorded in two wells of Tianjin are studied from different angles.Because of the different geographical position,geological structure,depth and aquifer rock,coseismic groundwater level changes of the same earthquake in the two wells are different.The result indicates that groundwater level is sensitive to distant earthquakes and not to near earthquakes and local earthquakes.The amplitude of coseismic groundwater level wave is related to magnitude and epicentral distance of the earthquake.The well' Ability for coseismic effects and for earth tide is different.