The invention discloses an automatic circulating water car washing device, and relates to the technical field of circulating water treatment. The automatic circulating water car washing device disclosed by the invention comprises a coarse filtration chamber, wherein one surface of the coarse filtration chamber is provided with a sliding slot; one surface of the sliding slot is connected with a sliding table air cylinder; one surface of the sliding table air cylinder is fixedly connected with a first motor; one end of an output shaft of the first motor is fixedly connected with a connecting rod; the circumferential side surface of the connecting rod is fixedly connected with four fan blades; one surface of each of the fan blades is fixedly connected with a corresponding hair brush; one surface of the coarse filtration chamber is fixedly connected with an electric telescopic rod; one end of the electric telescopic rod is fixedly connected with a filtration plate; one surface of a hollowcavity is connected with a coarse filtration plate in a sliding manner. According to the automatic circulating water car washing device disclosed by the invention, impurities remained on a filtrationdevice can be removed in time, the problem that water circulation treatment equipment is blocked because more impurities are remained on an existing filtration device is solved; and through sludge clearing devices, precipitants are totally pushed out of a filtration tank, so that the problem that the precipitants in the existing filtration tank is difficult to clear is solved.