SDN　(Software-Defined　Networking)　centralized　control　features　make　it　suffer　from　performance　bottlenecks　and　therefore　need　to　be　overcome　using　a　distributed　control　plane.　However,　the　imbalanced　load　among　multiple　controllers　will　also　lead　to　a　decrease　in　overall　system　performance.　In　order　to　solve　the　conflict　between　inefficient　nodes　and　overloaded　nodes,　a　more　efficient　and　flexible　load　balancing　algorithm　is　needed　to　ensure　the　efficient　operation　of　the　SDN　network.　The　algorithm　firstly　accurately　selects　the　controller　load　description　parameters,　then　uses　multiple　thresholds　to　distinguish　the　controller　status,　and　at　the　same　time　more　effectively　selects　the　switch　to　migrate　to　the　idle　controller.　The　algorithm　determines　the　state　of　the　controller　more　precisely　while　trying　to　make　each　controller　work　in　the　normal　mode,　to　avoid　the　controller　in　a　long　period　of　high　load　mode.　The　experimental　results　show　that　the　algorithm　can　effectively　improve　the　load　balancing　degree　and　throughput　recovery　speed　of　SDN　control　plane.