Abstract: A fuzzy TCP congestion control algorithm is proposed. The algorithm achieves better evaluation on network congestion by the way of combining the current and historical RTT changes which are used to adjust congestion window (CWND) with fuzzy controller, so that the problem of low throughput under abrupt congestion situations is solved effectively. The performance of the algorithm has been tested and evaluated on NS simulator and the simulation results demonstrate that the algorithm inspects network congestion more exactly and accordingly increases network throughput.