Abstract: Firstly, a one-side slip failure mechanism was proposed, wherein the foundation on slope behaves like a system of mesh-like rigid blocks with changeable velocities and directions in transition area. The velocity compatibility and plastic flow rule were satisfied by the corresponding velocity field. More optimization variables were introduced and a flexible failure mechanism was obtained by increasing the number of the rigid blocks. It was shown that some assumptions associated with the failure mechanism can be relieved, yielding a better upper bound solution for the bearing capacity factor. Secondly, calculation program was created using Matlab software. Calculation parameters were deduced based on the upper bound theory and geometric conditions of the failure mechanism and the velocity field. The calculation of bearing capacity factors were converted into a mathematical optimization problem when the object function and constrain conditions were established. Finally, the bearing capacity factors of foundation on slope were analyzed and the computation chart of Nγ and Nc was obtained. And, the influence factors of bearing capacity factor and the figures of the optimized failure mechanism and velocity field were also discussed.