An alkaline protease from Acetes chinensis was purified and characterized in this study. The steps of purificationinclude ammonium sulfate precipitation, ion-exchange chromatography with Q-sepharose Fast Flow, gel filtration chromato-graphy with S300 and the second ion-exchange chromatography with Q-sepharose Fast Flow. The protease was isolated andpurified, which was present and active on protein substrates (azocasein and casein). The specific protease activity was 17.15folds and the recovery was 4.67. The molecular weight of the protease was estimated at 23.2 kD by SDS-PAGE. With azoca-sein as the susbstrate, the optimal temperature was 55 °C and the optimal pH value was 5.5. Ion Ca2+ could enhance the pro-teolytic activity of the protease, while Cu2+, EDTA and PMSF could inhibit its activity. An alkaline protease from Acetes chinensis was purified and characterized in this study. The steps of purificationinclude ammonium sulfate precipitation, ion-exchange chromatography with Q-sepharose Fast Flow, gel filtration chromato-graphy with S300 and the second ion-exchange chromatography with Q- The specific protease activity was 17.15folds and the recovery was 4.67. The molecular weight of the protease was estimated at 23.2 kD by SDS -PAGE. With azoca-sein as the susbstrate, the optimal temperature was 55 ° C and the optimal pH value was 5.5. Ion Ca2 + could enhance the pro-teolytic activity of the protease, while Cu2 +, EDTA and PMSF could inhibit its activity.