Because the distributed architecture for traditional networks makes the load balancing technology difficult to meet the requirements of low cost, high flexibility and adaptive adjustment, a load balancing algorithm based on Software Defined Networking (SDN)in data center network is proposed to solve such problem. Firstly, according to the current load status of a path and its link load fluctuation,a weight is set for the path and as the basis for path selection.Secondly, a load balance degree is used to measure the network load status. Finally, for the flow that needs to be scheduled, its flow size range is further limited to ensure efficient flow scheduling. The simulation results show that, compared with other algorithms, the proposed algorithm can effectively improve the utilization ofnetworkresourcesandbalance the loadof the whole network.