Water temperature observation in wells,as a precursor observation project in China, aims to capture stress-strain information during the preparation of earthquakes. The study of the water temperature tidal effect has important significance, for water temperature tidal effect is both a reflection of stress-strain in crust and an interference factor of precursor observations. With a view of thermal conditions in artesian wells, the paper holds that there are two mechanisms for interpreting tidally induced water temperature changes in artesian wells. Namely, thermal conduction mechanisms and thermal convection mechanism. The paper then derives the quantitative relationship between water temperature and tidal volumetric strain changes in an ideal artesian well. Finally, the water temperature tidal effect in the Benxi artesian well is analyzed. The results show that the water temperature tidal effect in Benxi well is the result of joint action of thermal conduction mechanism and thermal convection mechanism, in which thermal conduction mechanism plays a leading role.