Currently, the application of bag-filter technology in controlling diesel exhaust particulate emissions has been close to practical stage. As one of the key links in bag-filter technology, engine exhaust cooling can directly influence working safety of the entire exhaust particulate filter system. Thermodynamic calculations and experimental research of water-cooled chiller has provided a feasible basis for water cooler to be used in actual diesel exhaust particulate emission control system. The cooler can make engine exhaust temperature drop from 400 to 180 . Even when engine works in high-speed and high-load condition, inlet exhaust temperature of cooler can descend from 500 to 190 or so after cooling, which can still meet bag-filter system requirement of below 200 .