In this paper, circuit simulation was chosen as the main methodology for research on the characteristics of electromagnetic rail launcher (EML or railgun) system. Nevertheless, the simulation model was not merely built on the static electrical characteristics. Moreover, practical physical processes contributed to the system have also been taken into consideration and expressed as electric parameters. Thus the description of a relatively complex system could be realized by a comparatively simple manner, and the simulation result is more accurate and reliable compared with the traditional circuit simulation ones with static electrical characteristics. A circuit simulation model of an EML system based on PSpice software was built, in consideration of multi-field characteristics, such as current skin effect, contact pressure and contact resistance on the contact surface of the armature and the barrel, velocity skin effect, friction drag and temperature coefficient of electrical resistivity. Simulations were made based on the improved complex model. Last but not least, comparison between the simulation results and the experimental ones was made to verify the accuracy and effectivity of the improved model.