The invention relates to a solar cell panel cleaning device and a working method, and belongs to the technical field of solar new energy auxiliary equipment. The device comprises a beam and a mobile car, wherein idler wheels are arranged at two ends of the beam; the mobile car is connected with the beam; a cleaning brush is arranged at one side of the mobile car. The beam is arranged at two ends of a solar cell panel; the idler wheels at two ends of the beam are in contact with the solar cell panel and can carry out rolling motion; the mobile car moves along the beam; the movement direction of the mobile car is combined with that of the beam; and the whole solar cell panel can be covered and cleaned by using the cleaning brush. The solar cell panel cleaning device is simple in structure, convenient to install, small in volume and occupied space, safe and stable, the solar cell panel can be cleaned in batches, cleaning is comprehensive and thorough, and the solar cell panel cleaning device can also be suitable for different operating environments and is wide in adaptability.