The resource utilization of industrial waste is a hot issue in the world. The harmless modification of phosphogypsum (PG) and its application in soil improvement is one of the key measures to alleviate the massive accumulation of wastes in phosphorus chemical industry. This paper first reviewed the effects of PG use in agricultural soil improvement, such as in regulating acid and contaminated soil, supplementing soil nutrients and improving nitrogen use efficiency, alleviating continuous cropping obstacles, promoting crop growth, reducing greenhouse gas carbon emissions, and environmental risks in the long-term direct return process. The harmless modification technology of PG in the process of agricultural utilization was systematically overviewed from the aspects of physical, chemical, biological and other technologies, and the main function mechanisms of modified PG were further expounded (anion adsorption, pH regulation, increasing efficiency and slow release, regulation of microbial environment in root zone). Finally, the scientific problems to be solved in the process of agricultural utilization of harmless modified PG were summarized to provide rational basis for future research of PG and sustainable development of phosphorus chemical industry in our country.