Aiming　at　the　problems　of　voltage　fluctuation　and　harmonics　in　photovoltaic　grid　connection,　the　improvement　of　a　three-phase　rectifier　circuit　is　proposed,　and　the　results　are　verified　by　MATLAB　simulation.　At　the　same　time,　this　paper　also　puts　forward　the　application　of　a　three-phase　four-wire　three-level　parallel　APF　structure　and　Three-term　rectifier　PWM　rectification　technology.　By　compensating　harmonic　current　generated　by　APF　and　controlling　the　switching　state　of　the　inverter　by　PWM,　the　bidirectional　flow　of　electric　energy　can　be　realized,　and　the　harm　of　harmonic　and　voltage　fluctuation　of　photovoltaic　grid　connection　can　be　solved.　　©　Published　under　licence　by　IOP　Publishing　Ltd.