The invention discloses a three-phase unbalance compensation apparatus based on fuzzy PI control. The apparatus herein includes a positive sequence compensation network, a negative sequence compensation network and a control module. The positive sequence compensation network brings an inverter AC side voltage source u and a system side voltage source us through an inverter equivalent resistor R and a series reactor L. The negative sequence compensation network brings an inverter AC side voltage source u into connection with the inverter equivalent resistor R and the series reactor L. The positive sequence control and the negative sequence control are under overlapping control. The positive sequence control uses ([Theta]<1>-[phi]<1>) uses indirect current control. The negative sequence control uses ([Theta]<2>-[phi]<2>) phase and modulation ratio to control negative sequence current and phase. The PI control module uses fuzzy rules and a fuzzy inference module to perform control so as to realize reactive compensation and three-phase load balance of a power distribution network.