A cutting simulation algorithm of spiral bevel gears was put forward to verify the movement in the CNC machine cutting process. The algorithm separated the cutting process into a series of discrete cutting movements. The cutting movement number was quantified by computing the amount of cutting blades. For any discrete movement, the algorithm interpreted the cutter blades and the spiral bevel gear as cones and layer circles respectively. So the data points on the gear tooth surface were generated by calculating the intersection points of the cones and circles. The algorithm adopted analytic calculation and was applied on the multiple cutting movements simulation of the spiral bevel gear. The programming languages were used to develop the algorithm and fit the tooth surface data points into NURBS surface of solid model. The cutting simulation results showed good precision and better efficiency compared with those in CAD/CAM software.