The network condition of the vehicular self-assembly network is critical, and in case of congestion, message transmission is blocked, which may lead to road accidents and traffic congestion in more emergency situations. However, the data propagated in the VANET network is transmitted in the form of single-hop broadcasts, but as the number of road vehicle nodes increases, each node sends safety messages at a periodic frequency, resulting in a large amount of data redundancy. In this paper, we consider the road vehicle density as the adjustment parameter for the safety message congestion control study and propose a congestion control method based on the regional hazard. In addition, a dynamic reliability evaluation scheme is proposed in order to verify the effectiveness of safety messages sent by vehicle nodes under the congestion control strategy. The simulation results show that the method can perform congestion control reliably.