Abstract: The gravity-type anchor block, one of the main important anchorage types of suspension bridge, has advantages of wide range of application and low demand for the bearing capacity of foundations. In the calculation of bearing capacity of gravity-type anchor block, the gravity and frictional resistance are taken into account while the resistances generated by the interaction of substruction and foundation as well as the gravity of backfill soil are neglected. It cannot be denied that the omission causes great error on the estimation of bearing capacity and the anti-sliding coefficient of gravity-type anchor block. Through analyzing the difference of the bearing behavior between the conventional anchor blocks and the rugged ones, the estimation method of the bearing capacity of gravity-type anchor block was studied in this paper. And the bearing capacity estimation formula and the using condition as well as the parameter estimation method are provided as well. Conclusions are draw as follows. Firstly, the bearing capacity generated from the base friction, the rugged surface pressure and the gravity of backfill soil. Secondly, comparing with the conventional estimation method, capacity obtained from the modified formula is improved tremendously. This phenomenon tells us that the gravity-anchorage can be optimized immensely. Taking the project of Xiang-Li Tiger Leaping Gorge, the volume of anchorage can be decreased 2.7%~75.6%. And the anti-sliding coefficient calculated from the conventional method is 2.42,while the modified one is 3.69.