Abstract: The deposit of phosphorus gypsum has been a problem for a long time.The main direction of comprehensive utiliza- tion of phosphorus gypsum is to be used as cement retarder.However，due to the small amount of harmful impurities in the phosphorus gypsum，and the difficultpurification，its application performance is poor than the natural gypsum，and its applica- tion in cement industry is still not in large scale.The mechanism of phosphorus gypsum used as cement retarder was discussed，the research progress and purification process of phosphorus gypsum in recent years were summarized， and it proposed that the reasons that limit the use of phosphorus gypsum were mainly due to the high cost of purification and the industry′s failure to form a unified standard.

Key words: phosphorus gypsum, cement retarder, purification process