The previously optimized crude alkaline protease from the haloalkaliphilic Bacillus circulans L. was partially purified using ammonium sulphate fractionation and dialysis. The best specific activity (27.7 U/mg protein) was obtained at 80% saturation. The optimum reaction temperature and reaction pH was 47℃ and 9, respectively. The enzyme activity was enhanced with Ca and K chlorides but suppressed with HgCl₂ and EDTA. The partially purified protease showed strong proteolytic activity on sheep wool and chicken feather. Also, the enzyme was compatible with the common detergent Tide and could improve its cleaning power in removing blood stain. These findings support the application of the present alka-line protease in biotechnological industries.