With the development of cloud computing, recently data center network has been a hot research topic in both academia and industry. Modern data center network is commonly organized in multi-rooted tree topology, such as fat-tree, with multiple available paths to provide high bisection bandwidth. Since the traditional load balancing scheme such as equal-cost multipath routing is not suitable for highly dynamic and bursty traffic in data center network, many load balancing mechanisms have been proposed. In this study, based on the fundamental research problems of load balancing in data center network, the international and domestic research progress of this area is introduced, including central controller-based, switch-based, and host-based load balancing schemes, and then the research trend of load balancing is prospected in data center network.