In the photovoltaic inverter system,due to the influence of power grid, the instantaneous input power and instantaneous output power of the inverter are unbalanced, resulting in two power disturbances on the input side of the inverter.A novel power decoupling structure with film capacitance is proposed in this paper. It is parallel to the input side of the flyback inverter, and the two power disturbance is transferred to the film capacitance through the charge and discharge of the film capacitor.The film capacitors have many advantages, such as small capacitance, small volume, long life and so on. It can replace the traditional electrolytic capacitors with large volume and short life. It also can filter out secondary power disturbances and prolong the life of the system. The feasibility is verified by PSIM simulation and experiment.