High quality calcium sulfate whiskers（CSW）were prepared from high purity natural gypsum as raw material byhigh pressure hydrothermal method.The gypsum raw materials and calcium sulfate whisker products were analyzed and char?鄄acterized by conventional analytical methods，XRD and scanning electron microscopy（SEM）.The results showed that the op?鄄mass，and the adding amount of H2SO4 was 1.0% of the water volume and reaction time was 4.0 h，then the calcium sulfate whiskers were obtained by rapid filtration and drying.The analysis results showed that the maximum length of CSW was 280.4 μm，the minimum was 19.59 μm and the average length was 80 μm.The maximum diameter of CSW was 5.86 μm，the minimum was 0.20 μm and the average diameter was 2.67 μm.Statistical analysis showed that the length?鄄diameter ratio ranged from 10 to 80.