Diesel generator exhaust gas purification can be divided into water spray purification and metal filtration purification. Water spraying purification is to spray water mist to mix with black smoke particles to purify black smoke, and the filtered water can be recycled. Metal filtration purifies the exhaust gas by filtering out the particles through a metal filter, and is equipped with a high temperature resistant automatic bypass valve, which will automatically alarm when the back pressure is too high, while the bypass valve will automatically open for emergency pressure relief to protect the engine operation safety. This item is custom designed according to the engine parameters.