1. According to the speed, it can be divided into high-speed (greater than 1000 rpm), medium-speed (300-1000 rpm) and low-speed (less than 300 rpm) diesel engines.
2. According to the combustion chamber, it can be divided into direct injection, swirl chamber and pre-chamber diesel engines.
3. According to the gas pressure action mode, it can be divided into single-acting, double-acting and opposed piston diesel engines.