The invention discloses an ICP-AES method for determining the sulphur content in a lead sulfate desulfurized product of a waste battery. The method comprises the following six steps: treating a sample; preparing to-be-tested sample solution and blank solution; preparing a standard work solution; drawing a standard work curve; determining the sulphur content in the to-be-tested sample solution and blank solution; and calculating the sulphur content in the sample. The method is simple and fast, accurate in result, and good in repeatability and reproducibility.