A decompression-dehydration-drying system was designed and improved to deal with cutting fluid wastewater produced during metal processing. The results show that the removal rate of total suspended solids is more than 99.38%, and the average removal rates of n-HEX, BOD5, COD_Mn, total nitrogen, total phosphorus, copper and zinc are 99.07%, 96.67%, 98.64%, 81.28%, 99.33%, 98.69% and 99.79% respectively. Combined with ozone treatment it can further improve the removal rate of organic pollutants. Compared with other treatment methods, during the process of sewage treatment, the proposed system produces very little smell and noises, and do not need a large number of chemical agents, and has a small footprint and low cost. It is especially fit for the treatment of highly concentrated cutting fluid wastewater.