GT-Suite software is used to establish the simulation model of high-pressure fuel injection system for diesel engine. Simulation parameters are modified based on the comparison with given experimental results. In order to improve diesel engine fuel injection performance, the cam profile was improved to ensure a high injection pressure and smooth operating characteristics. A more reasonable fuel cam profile was designed by analyzing the injection characteristics and dynamics. It improves the fuel mixture formation and combustion, so diesel economy and emissions performance are also guaranteed.