Abstract: In the past, the tooth surface contact analysis of spiral bevel gear was realized by two-dimensional tooth surface contact analysis. In order to obtain more intuitive tooth surface contact analysis effect, the three-dimensional tooth surface contact area of spiral bevel gear was obtained by numerical method. The mathematical model of spiral bevel gear is established based on the parameters of spiral bevel gear blank, cutter and installation adjustment. On this basis, the virtual assembly mathematical model of spiral bevel gear is established, and the mathematical model of virtual engagement is obtained. The contact trace and instantaneous three-dimensional contact ellipse contact in the process of spiral bevel gear meshing are solved by numerical method, and finally the three-dimensional contact area of spiral bevel gear tooth surface is obtained. The correctness of the algorithm is verified by an example.