A hydraulic simulation model was applied to the fuel injection system of diesel engine with controllable fuel starting injection pressure, and used to simulate injection process. The injector needle lifts and the injection pressure of high pressure fuel pipe at the injection end were recorded through expe-riments of the pressure fuel injection system with CB-466 combustion analyzer and brought into comparison with the computed results, thus verifies the simulation model and calculation method. Then, the model was used to discuss the effect of the fuel starting injection pressure on a diesel engine's injection characteristics. The results showed that in the condition of higher fuel starting injection pressure, the time of fuel starting injection was delayed, the pressure fuel injection was higher and the spray characteristics was improved.