The soil samples in a profile were collected around the pyrite slag pile site near a sulfuric acid plant in Guangdong province and the contents of lead were investigated detail. At the same time, the mechanism of lead pollution was principium analyzed. The research found that the lead pollutants were mainly concentrated in soils surface layer about 0-10cm and shown characteristics of contents rapidly decreasing along the uprights. the main factors that affected the transference of lead from the slag to the soil were the filtering by acid rain and itself acidification of the slag. Iron oxide colloid and organic matter may have been responsible for the lead retention in soil.