Abstract: A method according to this invention is used for washing waste phosphogypsum produced at decomposition of a mineral phosphoric raw material with sulphuric acid, wherein the said washing is carried on in countercurrent on a multi-zone filter; to the last zone of this filter there is supplied water while filter washings with highest concentration of the component being washed-off are returned to the decomposition stage. The essence of this method consists in that to the washing liquids there is introduced sulphuric acid solution of a concentration of sulphuric acid ranging within the limits from 20 up to 98 percent by weight of sulphuric acid in the amount of 1 to 30 percent of sulphuric acid amount used for decomposition of a phosphoric raw material.