In order to analyze the effects of geometric parameters on the stiffness of bolted flange joint, a parameterized model of bolted flange joint was constructed by using PCL (Patran Command Language) on the platform of software MSC.Patran. The law of the stiffness of bolted flange joint with the change of geometric parameters was studied, and the sensitivity of geometric parameters was analyzed based on the parameterized model. The results show that the ratio of the location of hole is the most sensitive factor to the stiffness of bolted flange joint, and the next one is thickness of upper flange. When the length of upper body is up to a const, the stiffness of bolted flange joint is insensitive to the length of upper body, and this conclusion can provide a reference to simplify the dynamic model of joint.