Simulation of railguns using the finite element method (FEM) is an alternative method for experiments, in the literature. Besides having many advantages, the FEM is complicated and time-consuming, especially for optimization. The circuit model method, unlike FEM, is simple, fast, and suitable for sensitivity analysis and optimization purposes. In this article, first, the circuit model is explained, and then, differential equations describing the behavior of the railgun have been derived and the equations have been solved by using the fourth-order Runge–Kutta method. The sensitivity of the railgun launching features to its parameters’ changes has been analyzed, which is an important issue that helps to design the railgun. Then, by using the particle swarm optimization (PSO) algorithm, single-objective and multiobjective optimizations have been done to maximize railgun outputs, such as velocity, efficiency, and force exerted on the armature at the moment of launching. Finally, for the validation of the proposed method, 3-D FEM has been employed. The results show the accuracy of the method. [ABSTRACT FROM AUTHOR]