The steering knuckle is one of the main parts on the steering axle of the car, which enables the car to run stably and sensitively convey the direction of travel. One function is to effectively transmit the angle value of the steering wheel rotation to the front wheel of the car, to control the route of the car in time to ensure the safety of the car; the other function is to bear the front load of the car, support and drive the front wheel to rotate around the kingpin. In the driving state of the car, it bears a variety of impact loads. Therefore, the steering knuckle not only requires reliable strength, but also must ensure its high machining accuracy. Its geometry is more complicated, more geometric shapes need to be processed, and the positional accuracy between each geometric surface is higher, and the processing precision will affect the steering precision in the running of the car.