Abstract: SDN can achieve high-quality QoS routing, but the forwarding nodes need the controller to issue flow tables for forwarding, its ability to respond to path failure problems in a mobile network is not strong, which is easy to cause a sharp drop in throughput, affecting the quality of surveillance video. In this regard, an SDN multi-path transmission method that dynamically adjusts the traffic ratio of each path is proposed. Each time the controller actively updated the network view, it preadjusted the traffic ratio of each path in the next time period according to the node location and link bandwidth, so as to reduce the amount of data transmitted by the vulnerable path in advance. The simulation results show that compared with SDN multipath transmission that adjusts the path after the link fails, this method improves the throughput and enhances the transmission stability.