In this paper, we will use the bidirectional A * algorithm in the urban environment of UAV for route planning, compared with the traditional A * search algorithm, bidirectional A * search algorithm can improve the search efficiency, and greatly save the time of route planning, and to solve the shortage that bidirectional A * algorithm now has, we improved bidirectional A * algorithm, synchronous bidirectional A * search algorithm is proposed in this paper, Through the programming to realize the forward search and the backward search working on the same time, and using the grid method to build the environment model for UAVs, when building the environment model we will fully considerat of urban environment to determine the grid size. Through experimental verification, the synchronous bidirectional A * algorithm can planning the route faster for UAVs and the route can be flew, compared with bidirectional A * algorithm, the synchronous bidirectional A * algorithm is faster and more efficient in the path planning.