To alleviate the occurrence of flow table overflow in SDN network, this paper studies the flow table overflow mitigation strategy based on network flow path optimization. This paper first describes the phenomenon of network flow table overflow and its causes, and analyzes the existing solutions. Then, based on the centralized control function of the software-defined network controller, a Flow Table Resource-based Routing Algorithm (FTR) is proposed. The algorithm mainly includes three parts: calculating the load factor of the switch, evaluating the balance degree of the network flow table, and calculating the link weight and routing. Finally, the effectiveness of the improvement measures proposed in this paper is verified by simulation.