When node density of vehicle Ad-hoc network（ VANET） is high

the number of channel collisions increases occurrence of congestion in VANET. To solve this problem

a dynamic power control algorithm is proposed. The network condition of nodes is evaluated by the value of channel busy ratio（ CBR）. In case of network congestion

the congestion information is flooded

so that other nodes can adjust transmission power accordingly. Moreover

a power control function is designed

in which power coverage and the number of covered nodes are considered. The simulation results show that this method can adaptively adjust the transmission power and performs well in reducing the probability of channel overload and improving the packet reception rate.