The invention provides a tray cleaning machine, which comprises a support, a first conveyor belt, a second conveyor belt, a third conveyor belt, a tray separating mechanism, a touch control screen, awater tank, a water inlet valve, a water outlet valve, a cleaning chamber, a forklift discharging station, a tray, a tray lifting mechanism, an observation window, rolling brushes, a synchronous motor, water delivery pipes and water spray nozzles. The first conveyor belt is arranged above the left side of the support; and the tray separating mechanism is arranged under the right side end of the first conveyor belt. According to the tray cleaning machine provided by the invention, through arranging the two rolling brushes, trays to be cleaned can be favorably cleaned for two times; through arranging the water delivery pipes and the water spray nozzles, the trays can be sprayed with water so as to be cleaned cleanly before cleaning, during cleaning and after cleaning; through arranging the tray separating mechanism and the tray lifting mechanism, the trays can be favorably separated and stacked; and through arranging the observation window, the trays during cleaning can be favorably observed, so that the tray cleaning machine is convenient to operate, high in automation degree, and thorough in cleaning.