With the rapid development of the 5th generation wireless communication technology, the broadcast features of wireless communication bring convenience to life, but also make the communication process has the risk of being intercepted and eavesdropped by illegal users. In order to protect the information transmission process, low probability of detection communication gradually attracts the attention of academia and industry. Different from the traditional fixed jammer assisted low probability of detection communication, mobile jammer assisted can greatly improve the scene adaptability of low probability of detection communication. This paper establishes a low probability of detection communication model based on vehicle-mounted mobile jammer, and uses beamforming technology to analyze the performance of low probability of detection communication in Rayleigh fading channel. Firstly, the error probability of test side is analyzed by hypothesis test and the optimal detection threshold is obtained. Then the average concealment probability of the model is solved according to the optimal detection threshold and the expression of interrupt probability is deduced. Finally, the optimization algorithm is designed with covert throughput as the optimization objective. Simulation results show that compared with fixed jammer, the performance of low probability of detection communication is improved by using vehicle-mounted mobile jammer.