Abstract: As a new energy storage element, supercapacitor not only could be used to meet the power balance in microgrid, but also could solve many power quality issues. But its low energy density determines other energy source should be considered to compensate its performance. A supercapacitor based united power quality conditioner (UPQC) in microgird is proposed, which is composed of supercapacitor, PV, bi-directional DC/DC converter, shunt inverter and boost-buck DC/DC converter. The structure and power flow model of this UPQC was analyzed. The control of the shunt inverter, the connection of supercapacitor and the shunt inverter and the charging circuit of the supercapaciter were introduced. The simulation result verified the effectiveness of the proposed circuit and control strategy.