With the Chinese power grid technology developed rapidly and the load applied on tower is going larger and larger, the tower base plate with eight anchor bolts has been used more commonly. Whilst the calculate theory is not comply with the actual condition. In order to make the calculate method more reasonable and reliable, The bearing capacity of Rigid tower base plate with eight anchor bolts is investigated through experiment and analytical parametric study was conducted to investigate the tower base plate by finite element method. Based on the result of experiment and finite element as well as classical mechanics theory, a new formula has been proposed which include the Equivalent calculating width and Equivalent calculating arm of force. This formula considered plate stiffness, post-buckling strength and subplate which influence the bearing capacity of tower base plate in this formula, thus the proposal formula is reasonable and effective, It is helpful in project design.