Abstract: For the traditional TCP congestion control protocol did not suit wireless Ad hoc networks, techniques were applied to provide wireless Ad hoc networks cross-layer congestion control improvement scheme (CCIM), including cross-layer design, optimization theory and extracting characteristic parameter from each layer of the protocol stack. In the CCIM, a new method was presented for congestion detection, making the input/output rate of MAC layer accord with the buffer queue length of network layer, and a model of the congestion control and random access was built to get the optimal transmission rate based on the mechanism of the ECN explicit congestion feedback and the expansion signal transmission. The NS2 simulation results show that the CCIM scheme can reduce the end-to-end transmission delay, and the network throughput and fairness are improved obviously.