In this article, internal forces of 300m3and 500m3inverted cone water tower tanks were calculated by membrane theory and moment theory,and internal force distribution of water tank was analyzed. The results show that the edge interference force makes some differences of internal force distribution of moment theory from that of membrane theory on the edge of tank,but the results of moment theory is closer to the real situation of the tank and moment theory can be used as a relatively accurate method theory for internal force calculation of inverted cone water tank. The results provide a useful reference for the design of similar projects.