Abstract: We make use of characteristics of CESE method(in CESE method, conservative variables as well as their spatial derivatives are regarded as independent marching quantity and solution points are on boundary of every control volume) and give a new method to clean magnetic field divergence by using the least-squares method. We also explore the influence of the weights of magnetic field divergence constrained equation on the results, by comparison, we found that when the weight of the equation is 1, the magnetic field divergence can be decreased efficienty.