Aiming at the problems that the communication overhead between controllers is large and the controller throughput is low during the load balancing process of multi-controller in Software Defined Network (SDN), a hierarchical controller load balancing mechanism was proposed. Based on the hierarchical architecture, the load balancing was completed through the collaboration of super controller and domain controller, and the predefined load threshold was used to reduce the message exchange overhead between domain controller and super controller. At the same time, the most overloaded domain controller was effectively selected. A plurality of switches conforming to the migration standard were selected from the switches controlled by the most overload domain controller. Simultaneously the selected switches were respectively migrated to a plurality of domain controllers with high overall performance, which solving the problem of load imbalance among multiple controllers. The experimental results showed that, compared with the COoperative Load BAlancing Scheme for hierarchical SDN controllers (COLBAS) and the Dynamic and Adaptive algorithm for controller Load Balancing (DALB), the number of messages in the proposed mechanism system was reduced by about 79 percentage points, and the throughput of the proposed system was about 8.57% higher than DALB and 52.01% higher than COLBAS. The proposed mechanism can effectively reduce the communication overhead and improve the system throughput to achieve a better load balancing effect.