The invention discloses a method for reducing phosphorus pollution in phosphogypsum filling process by using modified quartz sand, belonging to the technical field of phosphogypsum filling. The quartzsand is subjected to modification coating treatment, the modified quartz sand with different particle sizes is used as part of aggregate and added into the filling slurry, and the ion concentration is measured by taking the effluent of the filling slurry; when the phosphogypsum filling body has been cured for the 28 days, the toxic leaching experiment is carried out; it was found that the phosphorus concentration in the phosphogypsum filling body added with modified quartz sand could be reduced to less than 0.5 mg/L, which reached the first-class standard of phosphorus discharge in industrialwastewater. The invention can remarkably reduce the dissolution concentration of the pollutants in the phosphogypsum filling body, reduce the negative influence of the phosphorus-containing leachatein the filling body on the groundwater, is beneficial to the green recycling process of the phosphorus chemical waste, is beneficial to the development of the phosphate rock enterprise, and obtains good economic and environmental benefits.