In this paper, a multi-objective genetic algorithm based on the numerical simulation of the polymer flow is proposed to optimize the geometry parameters of the coat-hanger die with uniform outlet velocity and minimal residence time. The vector evaluated GA method is used to find the parameter values for obtaining the uniform outlet velocity and minimal residence time, where the manifold angle, the land height and the slot gap are chosen to be the design variables, the outlet velocity and the residence time are obtained by simulating the three-dimensional and isothermal polymer flow in the coat-hanger die. The stochastic universal sampling (SUS) is adopted to select the new population which is representative of a coat-hanger die. The optimal geometry parameters of the coat-hanger die achieved in the 30th generation among 20 individuals of each generation, which showed that the manifold angle and the gap slot were the most influencing design parameter on the coefficient of variation (CV) value of outlet velocity and residence time.