Abstract: The influence of the angle of the main diagonal of the transmission tower leg on the tower leg is studied and the appropriate angle of the main diagonal is given. The anti-torsional rigidity of the transmission tower under two different diagonal layout types,cross diagonal and inverted K diagonal,is compared and analyzed. The results show that the optimum value range of the main diagonal angle of the tower leg is 30°～40°；the anti-torsional rigidity of the tower arranged with inverted K diagonal is lower than that of the tower arranged with cross diagonal. When the torsion load is comparatively large,the cross diagonal layout is recommended.