When spray is injected form multi-hole nozzle, oil bundle is impinged on the inner conical-face orientation sleeve mounted on the outside of nozzle and diffuses along the cone-shape surface, and then the conical spray is formed. The impingement quantity of spray can be adjusted by changing the relative position between nozzle hole and impingement surface. Three-dimensional CFD package AVL FIRE 8.4 is used to simulate and analyze the diffusion characteristics of full-impingement conical spray, half-impingement conical spray and multi-hole free spray. The simulated results show that: comparing with free spray, inner conical-face impingement type conical spray has the characteristics of high diffusion and homogeneous circumferential dispersion. Combustion performance test, which is carried out on 135-type single-cylinder diesel engine, shows the following conclusions: half-impingement mode is better than whole-impingement mode; for half-impingement mode, 4-hole nozzle is better than 6-hole nozzle; appropriate fuel supply advance angle is good for achieving hot premixed combustion.