Peer-to-Peer file sharing applications, which enable peers to establish multiple TCP connections between other peers to transfer data, pose new challenge to congestion control. Since conventional congestion control only aims to make each of those connections TCP-friendly, self users can increase the number of connections to grab a large share of the bandwidth, introducing more congestion and degrading the overall network performance. To address this issue, in this paper we propose and design an aggregate congestion control mechanism called ACCM which enforces the friendliness of network upon all the connections belongs to an application instead of upon individual connection. By observing the share congestion in access link through application-level measurement technology, ACCM dynamically adjusts the window size of parallel TCP connections, achieving friendliness to the network on the basis of maximize utilization of network bandwidth. The simulation experiments demonstrate that certain fairness and congestion avoidance can be achieved in presence of congestion and the network bandwidth can be effectively utilized in absence of congestion with ACCM.