As one of the important bone regeneration materials, alpha-calcium sulfate hemihydrate (alpha-CSH) has attracted widespread attention. In this study, a facile method was developed to prepare a-CSH with low aspect ratio via high-gravity continuously reactive precipitation of a calcium sulfate dihydrate (CSD) precursor, using ethanol as a morphology modifier in a rotating packed bed (RPB) reactor, combined with CaCl2 salt solution method under atmospheric pressure with the addition of citric acid with a low concentration (0.06 wt %). The precipitation time of CSD powders in the RPB was dramatically shortened from 30 min to 1 s, and the precursor exhibited more regular short rod shapes and much smaller size, compared to that obtained in a conventional stirring tank reactor (STR). Furthermore, calcium sulfate bone materials with high stability and good mechanical property were prepared by mixing alpha-CSH and normal saline with a liquid solid ratio of 0.6. The RPB products had a higher compressive strength (2-3 times) than the STR counterpart.