This study established a food-grade Bacillus subtilis expression system for a maltopentaose-forming amylase derived from Bacillus megaterium STB10 (BmMFA). The enzymatic properties and product synthesis pattern of the expressed enzyme were studied. Results showed that BmMFAse exhibited excellent catalytic activity, and the enzymatic activity in the fermentation supernatant of B. subtilis was 196.57 U/mL. The optimal reaction temperature and pH of BmMFA were 50 ℃ and pH 7.0, respectively, and BmMFAse could adapt to a wide pH range. The action pattern of BmMFA was found to tend to be endo-type. BmMFAse showed superior product specificity, and the maltopentaose content in maltodextrin hydrolyzed by BmMFAse for 24 h was over 42%. The substrate conversion rate and the relative content of maltopentaose as the major product were higher using amylopectin as the substrate for BmMFA than amylose. This study provides a theoretical basis for the efficient production of maltopentaose.