Abstract: At present, TCP congestion control algorithm is widely applied to the Internet as a reliable data transmission protocol. When the credibility of data transmission is guaranteed, fairness among different TCP traffic flows is an important performance index of the network. Nowadays, the fairness algorithm among TCP flows has been proposed in a single bottleneck network, but few people have focused on the fairness among TCP flows in a multiple bottleneck link so far. Therefore, in this paper an enhanced TCP congestion control algorithm in multiple bottleneck networks is proposed and is realized in IP network in support of ECN mechanism in network layer. The simulation results demonstrate that remarkable fairness among TCP data flows in the multiple bottleneck networks can be achieved with the application of this algorithm. Furthermore, the supposed algorithm has higher throughput and faster response than the current TCP algorithm used. Therefore, the performance of this algorithm is better in multiple bottleneck networks than that of the current TCP algorithm used.