The short rigid piles are located on the top of slope and subjected to the incline load. Both the cross effects produced by horizontal and vertical loads and the effect of the slope are needed to be considered in the design. Because of several factors interacting each other, far more complex than that of piles installed in horizontal ground. This paper adopts three-dimensional finite element software and carries out numerical simulation analysis of composite piles by taking into account of many factors. The study finds that under the same load and with the increase of the angle of the composite load, the ultimate bearing capacity firstly decreases and then increases. The influence of the vertical load on the horizontal displacement of the pile is greater than that of the internal force. Increasing the pressure of soil around piles will lead to the promotion of pile displacement and internal force. With increasing of edge distance from the slope crest, the effect will decrease.