The most important function of a network is for transporting traffic. Due to the low traffic capacity of network systems under the shortest path routing algorithm, plenty of heuristic routing algorithms are emerging. In this paper, we propose a dual-routing algorithm model for network system. The overall traffic capacity of a network system can be evaluated by the critical packet generating rate. When this routing algorithm is adopted on BA scale-free networks with an appropriate parameter p, it can achieve larger traffic capacity compared with the single-routing algorithm.