The invention relates to the technical field of cleaning devices, in particular to an automatic cleaning device. The automatic cleaning device comprises a frame, a conveying mechanism, a cleaning mechanism and a moving mechanism, the conveying mechanism and the cleaning mechanism are erected on the frame, and the moving mechanism is connected with the frame in a sliding mode. The cleaning mechanism comprises a first box, a spraying assembly, a second box, a heating pipe and a first carrier, the first box and the spraying assembly are erected on the frame, the second box and the heating pipe are erected in the first box, and the first carrier is erected in the second box. The spraying assembly comprises a hydraulic pump and a liquid spraying pipe, and the hydraulic pump communicates with the second box and the liquid spraying pipe. In use, heat insulation liquid is injected into the first box, cleaning liquid is injected into the second box, a relay and other products conveyed by the conveying mechanism are transferred onto the first carrier through the moving mechanism, the heating pipe heats the cleaning liquid by heating the heat insulation liquid, the hydraulic pump pumps the heated cleaning liquid and sprays the cleaning liquid onto the relay through the liquid spraying pipe, accordingly impurities attached to the relay are washed away, the relay does not need to be manually cleaned, and cleaning efficiency of the relay is greatly improved.