Abstract: Objective:To study purification,gene cloning and enzymatic properties of extracellular protease secreted by Bacillus sp. L1. Methods:The extracellular protease EL1 was purified by ammonium sulfate precipitation,DEAE sepharose FF and then the enzymatic properties were determined. The extracellular protease EL1 was identified by mass spectrometry(MS). Results:The mass spectrometry results results indicated that the protease EL1 belonged to serine protease. The nucleotide sequence contained 1326 bp,encoding 441 amino acids,which was highly conserved to serine protease of Bacillus stratosphericu(WP_007499449)with 98% sequence similarity. The enzymatic properties results suggested that the optimum temperature of EL1 was 60℃ and the optimal pH was 8.0.The EL1 was stable and active at 60℃ and had a high stability at pH8.0. Mn²⁺ could activate the activity of EL1 to some extent and Cu²⁺ could inhibit it to some extent. Conclusion:The extracellular protease EL1 from Bacillus sp. L1 showed a good thermal stability and high stability in alkali sdution,which has potential industrial application value.