TCP Vegas can provide a better performance compared to the traditional TCP Reno scheme. However, when TCP Vegas and TCP Reno connections coexist and share the same link in wired network, there exists a serious incompatibility problem of unfair bandwidth sharing in favor of TCP Reno. To solve this problem, by adding monitoring algorithm of the network state based on relative queuing delay to TCP Vegas-A, an enhanced Vegas algorithm is proposed, termed TCP Vegas-A+. TCP Vegas-A+ can adjust the congestion window more properly and timely by classifying the network state into congestion increase and congestion decrease. We analyze the compatibility of Vegas-A+ and Reno connections by computing and comparing the congestion window size and the number of transmitted packets in congestion avoidance phase, and compare it with the compatibility of Vegas+ and Reno connections. Mathematical analysis and simulation results show that, TCP Vegas-A+ algorithm improves the compatibility with TCP Reno and has a better capacity in competition with the Reno for bandwidth than other improved Vegas algorithms.