Abstract: Original determination method of magnesium sulfate main content has imperfection.Namely,determined content of magnesium sulfate product is higher than the real content and there is a deviation.Based on the problem,improving plan was put forward in process of standard revision.Meanwhile,experimental verification was made and results were obtained.An accurate determination method of industrial magnesium sulfate main content was supported.This new method can make determined result reflect the real quality of products scientifically.