Aiming at the unsolved channel interference problems of multiuser concurrent communication in cognitive radio network, this paper introduces small scale multipath shape factors into modeling under Rician fading channel and systematically analyzes the channel interference that cognitive user conducts over the primary user. Numerical analysis indicates that multipath shape factor theory can effectively analyze the concurrent communication interference between cognitive user and primary user. Meanwhile, in meeting the need of primary Quality of Service (QoS), it can dynamically change the access number of cognitive user and improve the utilization of spectrum resource. The analysis model proposed in this paper can be used to optimize the application performance of cognitive radio technology in the complex scene of smart grid.