A novel protease gene from Bacillus gibsonii, aprBG, was cloned, expressed in B. subtilis and characterized. A high-level expression of aprBG was achieved in the recombinant strain when a junction was present between the promoter and target gene. Purified recombinant enzyme exhibited similar N-terminal sequences and catalytic properties to the native enzyme, including high affinity and hydrolytic efficiency toward various substrates and superior performance exposed to various metal ions, surfactants, oxidants and commercial detergents. AprBG was remarkably stable in 50% organic solvents and could retain 100% activity and stability in 0-4 M NaCl, which was better than the characteristics of proteases reported previously. AprBG was most closely related to the high-alkaline proteases of the Subtilisin family with 57-68% identity. The secretion and maturation mechanism of AprBG was dependent on the enzyme activity as analyzed by site-directed mutagenesis. Taken together, our results revealed that the halo-solvent-tolerant protease AprBG displays significant activity and stability in various extreme conditions, and is therefore potentially applicable in versatile biotechnology applications.