While the active distribution network has fully utilized the advantages of various clean energy sources, it has to face the dilemma of increasing power quality problems. The unified power quality controller can comprehensively deal with the voltage quality and current quality problems in the active distribution network. Firstly, the UPQC system is decoupled and controlled, and the mathematical model under dq coordinates is converted to the αβ coordinating system to achieve full decoupling. The transfer functions of the series side and parallel side converters are obtained. Then the controllers on the series side and the parallel side are designed respectively. Finally, the simulation model of the UPQC system is established.The simulation results show that the controller designed in this paper has better compensation effect under the condition of the voltage drop or suspension, load current distortion.