Abstract: The 802.11MAC protocol has been used widely in static multihop wireless network. It reduces the effect of hidden terminal for TCP performance, but it does not remove the effect of hidden terminal fully. But, the fairness of middle links will be affected due to the hidden terminal and make the throughput badly descend. This paper proposes a new way based on data retransfer ratio. When the data retransfer ratio increase, dynamic reduce the size of contention window of backofftimer, enhance the probability of use channel and improvement the TCP fairness. The simulational results show that the proposed algorithm can ultimately avoid the instability of TCP flow and increase the fairness of middle links.