Abstract: This study aims to optimize the prokaryotic expression of hyastatin gene in Scylla paramamosain. The fragment of cloned mature peptide in S. paramamosain hyastatin was ligated with the expression vector pET-28a. This recombinant was transformed into Escherichia coli BL21(DE3), and the gene was expressed by inducing under the optimal conditions. The expression of this protein was the highest under the 37℃ and in 0.2 mmol/L of IPTG for 4 hours. The molecular weight of the expressed product was identical to that of expected protein by SDS-PAGE analysis. The fusion protein was efficiently expressed as inclusion bodies, and further purified by HisTrap HP column. The result of Western blot showed that the fusion protein could be bound specifically with mouse anti-His-tag Mab. In conclusion, the prokaryotic expression product of hyastatin gene in S. paramamosain may be obtained by optimizing expression conditions.