Abstract: Expanding application of IEEE 802.11 distributed coordination function (DCF) protocol to vehicle networks(VANETs) will greatly quicken the development of Vehicle networks. However, 802.11 DCF endures severe fairness problem in some scenarios, which would limit it's performance in vehicle networks. Most existing fairness solutions aim at long term fairness issue but not the short term fairness problem which is more popular in vehicle network. In this paper we discuss how the distance between two pairs commnicating vehicles affect the short term fairness . By simultaion we validate that the two-way road communication exhibite fairness problem only under two situations. Based on this result, a power adjusting scheme is proposed. The simulation results show that the fairness problem is solved by our power adjusting strategy.