Abstract: This paper analyzes the impact of wellbore storage effect on the well tide and that of transmissivity and storativity on tidal drainage response so as to discuss the origin for changes of well tide. Through tidal analysis of water level data monitored in the well Chuan06, and judgment of undrained response, we obtained amplitude response (A) and phase shift (η) of tidal constituents M₂ and O₁ caused by the wellbore storage effect by removing the influence of fracture effect, and then comparatively analyzed Hsieh model and the actual relation between A and η. The results show that the changes in the well tide could be attributed to the changes in the wellbore storage effect, where as the changes in the hydraulic response were mainly attributed to the changes in transmissivity rather than that in storativity.