High pressure common rail (HPCR) injection system not only enables the diesel engine to meet the increasingly strict emission criterion, but also enhances its economic efficiency and comfort ability. Its simulation model is established in AMESim environment and it is calibrated to ensure the accuracy. The influences to cycle fuel injection quantity (CFIQ) of electromagnetic valve lift, control piston clearance, needle valve lift, open pressure and flow coefficient are analyzed in details with the simulation model in the whole working conditions. The results show that electromagnetic valve lift, needle valve lift, open pressure and flow coefficient are the key characteristic parameters on fuel injection quantity fluctuation (CFIQF).