The invention provides a method for improving the coating quality of an oriented silicon steel Mgo isolating agent. The method comprises the following steps that in the preparation process of Mgo slurry, a defoaming agent accounting for 0.01%-0.5% by weight of water is added, and then the Mgo slurry coats the upper surface and the lower surface of strip steel by using a roller coating type coatingmachine. According to the method, the defect of strip steel longitudinal stripes generated during coating of the oriented silicon steel Mgo isolating agent is overcome, so that the surface coating uniformity is improved, the method is simple and convenient to operate, low in cost and free of pollution to the environment.