The utility model discloses a diesel engine piston which is made of steel or cast iron. The diesel engine piston comprises a piston body, an omega-shaped combustion chamber and piston ring grooves, wherein the combustion chamber is arranged at the top of the piston body, the depth of the omega-shaped combustion chamber ranges from 5 mm to 100 mm, the radius of the transition circular arc between the combustion chamber and the piston top ranges from 2 mm to 10 mm, and the transition circular arc radius of the bottom of the combustion chamber ranges from 5 mm and 100 mm; the piston ring grooves are formed in the peripheral surface of the piston body in parallel. The diesel engine piston is simple and reasonable in structure; the existing aluminum material is replaced by the steel material, and the compression highness is small, so that the height of an engine is reduced, and the weight of the engine is reduced and the requirement for space is lowered; meanwhile the diesel engine piston can bear a high temperature, so that higher combustion pressure in a cylinder of the engine can be achieved.