Abstract: A modeling and analysis scheme based on Markov chain for Random Access MAC (RA-MAC) protocol of cognitive radio networks are proposed. A three-state Markov chain model of channel is presented, while the problem of dynamic characteristic of channel is dealt with by introducing the channel constraint rate and the available channel number of stability. A channel negotiation model is designed based on discrete two-dimensional Markov chain. An algorithm to evaluate the saturation throughput of RA-MAC is presented, considering constraints of capacity of the control channel. The simulation results demonstrate the effectiveness of the proposals, and the relationship between protocol performance and parameters is analyzed.