The effects of reaction temperature, reaction time, liquid-solid ratio, pH value and Na2SO4 mass fraction on the generation of α-CaSO4·0.5H2O were investigated using Na2SO4 solution as the reaction medium. The results show that α-CaSO4·0.5H2O crystals with an average length of 46.0 μm, an average aspect ratio of 17.23 and a homogeneous morphology are prepared under the conditions of Na2SO4 mass fraction of 12.5%, liquid-solid ratio of 5∶1, pH value of 7, reaction temperature of 97 ℃ and reaction time of 4 h. The method of chloride-free salt solution under atmospheric pressure overcomes the drawbacks of chloride ion corrosion of industrial equipment and environmental pollution, providing important technical support for the high value utilization of phosphogypsum.