Abstract: In order to mitigate the congestion of Ad Hoc network, a novel active queue management method is proposed.In this method, transition probability matrix is presented base on discrete time Erlang loss system at first, and the mathematic formula of average queue length is derived.Then, the drop strategy is designed with node service rate and traffic arrive rate, and a simulation was conducted to research on the relationships between drop rate and utilization rate.The result shows that drop rate is positive correlation with utilization rate.