The uniform magnetic fields are correlated with the region relative to coil systems, the arrangement of coils, the dimensions of coil systems and the number of ampere-turns. It has been the very considerable difficulty encountered in the past in attempting the numerical solution of the equations involved, especially a region under coil systems. The paper considers the uniform degree of magnetic field of the region given as the objective function and uses differential evolution algorithm to search the position for arranging coil systems, the dimensions of coil systems and the number of ampere-turns to make the objective function reach the optimum. The result shows that the problem of uniform magnetic fields produced by rectangle coil systems can be solved effectively with differential evolution algorithm.