The cut size of the wheel bucket sand washing machine and spiral sand washing machine is between 150 – 300 μm usually, which leads to the lost of some fine sands from the overflow of sands washing machine and relative higher fineness modulus of products from sand washing machines and missing of fine particles grading. Recovering fine sands from the fine sands in the overflow of sands washing machines through cyclone can on the one hand increase the yield of sands products and on the other hand supplement the fine particle’s constitution of the finished sands so as to improve the finished sands grading performance better.