The invention discloses a solar energy and mains supply complementary household power generation system and a control method thereof.The power generation system comprises a storage battery, a photovoltaic module, an illumination sensor for detecting current illumination intensity, a clock module, a storage unit, a voltage detection module, an illumination treatment unit, a solar energy charging controller and a mains supply charging controller, wherein the illumination treatment unit is connected with the illumination sensor, the clock module, the storage unit and the voltage detection module and used for controlling the system; the solar energy charging controller is connected with the illumination treatment unit and used for controlling the photovoltaic module to charge the storage battery; and the mains supply charging controller is connected with the illumination treatment unit and used for controlling mains supply to charge the storage battery.The method for controlling the power generation system comprises the steps of judging whether the effective light intensity moment arrives, and comparing the actual to-be-charged amount and the theoretical to-be-charged amount of the storage battery.According to the control method, the rechargeable amount of solar energy and the actual to-be-charged amount of the storage battery are compared, and the solar utilization rate is improved.