Abstract: In this paper, the problem of reactive power loss caused by uneven power distribution of the system caused by the uneven power distribution of the three-phase unbalanced condition in the distribution network is studied, and the static synchronous compensator (STATCOM) is used to compensate the reactive power of the power grid, and the regulated voltage is restored to stability. In this paper, a simulation model is built in MATLAB/Simulink to observe the reactive power change of the STATCOM compensation system, and the change of positive and negative zero sequence voltage and current under the condition of three-phase unbalanced operation is analyzed. The results show that the improved fuzzy PI control model can quickly respond to the change of system reactive power and compensate for the system reactive power.