Fuel injected from multi-hole injector with a small injection angle (100°) is impinged to the multi-impingement-wall head(MIW head), which is located in the center of combustion chamber and is attached to the cylinder head. The fuel is diffused into the piston cavity to form a three-dimensional diffusion spray. The main advantage of diffusion spray is that the effects of the fuel impinging diffusion and the collision between fuel particles can be obtained. Based on the concept of MIW head, the experimental results show that the combustion performance and the fuel consumption have been improved. Besides, the NOx, HC and smoke densities of the exhaust gas of a diesel engine have been reduced.