Abstract: The preparation of high-strength α-hemihydrate gypsum with high value-added is an important way to expand the utilization. The crystal morphology and particle size of α-hemihydrate gypsum are important factors affecting its mechanical strength. Here, we investigated in deep the influence of the malic acid addition and the glycerol concentration on the crystal morphology and particle size with the reaction medium of glycerol solution and the crystal modifier of malic acid. It was found that malic acid regulated the crystal morphology by complexing adsorption with the calcium sites on the surface of α-hemihydrate gypsum crystal. The main function of glycerol was to control the crystal size, which was not achieved by glycerol adsorption directly on the surface of the crystal or affecting the adsorption of malic acid. Finally, crystal morphology and particle size of α-hemihydrate gypsum were synergistically controlled by adjusting malic acid addition and glycerol concentration, and the crystals with similar morphology and different particle size were prepared. The crystals with average size of about 18 μm were prepared with the glycerol concentration of 45% and the malic acid addition of 37.09×10^-4 mol·kg^-1. Meanwhile, the crystals with average size of about 5 μm were generated with the glycerol concentration of 75% and the malic acid addition of 18.54×10^-4 mol·kg^-1.