Abstract: Bacillus expression system as gene engineering expression system has many advantages such as excellent secretion ability, successful heterologous protein expression system, not forming inclusion bodies, non-endotoxin, so it is widely studied and applied, many kinds of industrial enzymes were expressed in Bacillus subtilis expression system. In this review, it mainly talks about the advances, characters and application of Bacillus expression system, and presents a solution to the defects in the expression system of Bacillus, offering the main research directions for Bacillus expression system.