Abstract: By an integrated numerical-experimental approach, fundamental aspects of CR system dynamics were investigated, paying specific attention to the multi-injection fuel quality fluctuation induced by water hammer with dwell time (DT). The model of high pressure common rail injection system model was built based on AMESim package and the simulation was implemented using the data of experimental injection rate. The hydraulic process of control chamber and delivery chamber, as well as the lift process of pilot and needle valve were simulated and analyzed under the impact of water hammer wave. It is summarized that the multi-injection fuel quantity fluctuation is caused by synthetic cyclical factors of needle opening and closure delays, and injection pressure due to the impulse of water hammer.