There are some shortcomings of traditional power communication network, such as low routing efficiency and high cost. Thus a QoS routing strategy based on an improved ant colony algorithm is proposed on the basis of a software defined network. A routing model with delay, number of paths and jitter as constraints is established, and an improved ant colony algorithm is used for path selection. The end-to-end delay, packet loss rate and link utilization are compared by simulation and traditional routing strategies. The results show that, compared with the traditional strategy, the load distribution of the strategy is more uniform, and the performance of end-to-end delay, packet loss rate, link utilization and so on are significantly improved. This suggests good potential for practical application. This work is supported by the Natural Science Foundation of Hebei Province (No. F2015502047).