Sand washing machine is widely used in metallurgy, construction and hydropower industry for washing, classify and purification working. It is applicabel to wash the fine granularity and coarse particle size materiel. It is especially applicable to wash construction sand and paving sand. This sand washing machine has the features of reliable structure, convenient maintenance, big capacity, low power consumption, high cleaning level. The new sealling structure, totally closed oil bath type drive device and adjustable overflow weir plate promises that the machine works efficiently.