In order to investigate the dynamic characteristics and influence factors of reciprocating pump, a modular model library of the RPFPS (reciprocating pump-fed propulsion system) was established. The modular model library was built on the basis of lumped parameter approximation and the dynamic simulation of the work process for RPFPS was carried out on the basis of the AMESim system. The effects of initial pressure of accumulator, equivalent volume of pipeline under gas generator and number of nozzles on the dynamic characteristics of reciprocating pump were studied. Results have been obtained as follows: due to the bigger initial pressure of accumulator, less time was used to start the reciprocating pump, but the regulation ability of accumulator was weaker; it would take less time to start the reciprocating pump because of larger equivalent volume of pipeline under gas generator, but it would also lead to the increase of pressure fluctuation; the greater the number of nozzles, the lower the pressure fluctuation in gas generator, and the more time of reciprocating pump to start because of the slower pressure increasing speed.