How to improve the network traffic capacity (load), in complex networks with the connection edge by which the transmission capacity (bandwidth) is limited, is the main subject of the research in this paper. We propose a heterogeneous bandwidth allocation scheme under the condition of the fixed total bandwidth resource of the network. With an appropriate proportion of 'controlled edge', the bandwidth resource is reallocated in the network. According to the data flow model, with congestion awareness routing strategy, bandwidth allocation we proposed can adjust the data flow and improve the efficiency of bandwidth utilization. Finally, the network traffic capacity is significantly improved compared with the one in the homogeneous bandwidth allocation. Meanwhile, it does not destroy the premise of the network topology by using our bandwidth allocation. In this paper, we make a series of simulation using the heterogeneous bandwidth allocation in the Barabsi-Albert scale-free network and the Watts-Strogats (WS) small world network, and find that there is a strong correlation between the network traffic capacity and the bandwidth of vertex in the WS network.