The influence of modified phosphogypsum on the setting time and strength of ordinary portland cement was studied by small mill test, and the proportion of cement produced by modified phosphogypsum in winter and summer was determined. The production practice shows that the cement products produced by phosphogypsum with pH value of 7~13 completely meet the requirements of national standards, and the setting time can be adjusted widely. The application of modified phosphogypsum not only digested the industrial waste residue, but also reduced the production cost, which brought good social and economic benefits.