Electromagnetic gun can customize appropriate projectile according to the vulnerability of individual target. For an aim velocity of projectile， different voltage， current， and dimension of rails， which formed solution space with multiple feasible ones， and the optimal solution should be found. Based on non-dominated sorting genetic algorithm-II（NSGA-Ⅱ）， taking the muzzle velocity and energy efficiency as the goal， four multi objective optimization problems are proposed， in which projectile mass， dimension of rails， capacitance， voltage and current of electric power， are involved progressively. Based on Pareto optimal solution that solved with NSGA-Ⅱ， the main influence factors were analyzed， and some useful conclusions were drawn.

Simulation research on triggering current is the kernel of electromagnetic railgun investigation， based on its equivalent electric circuit， the models of pulsed power， rail， armature， sliding electrical contact between armature and rail are established， and the electromagnetic railgun simulation model is established by integrating the component models together. By means of Dommel-EMTP（electromagnetic transient program）algorithm， the triggering current and voltage of every pulse forming unit are simulated， then the total discharging current， velocity and displacement of armature are solved. Compared with the tested date， the relative error of simulation results of total discharging current and armature muzzle velocity is less than 4% ， which indicates the effectiveness and accuracy of the model and provides basic method for further research on electromagnetic railgun.