The invention relates to the technical field of microorganisms, and in particular relates to a bacillus velezensis and an application of the bacillus velezensis in preparation of a tobacco flavor. Thebacillus velezensis JXQ21 provided by the invention has a preservation number of CGMCC NO.17833. The content of flavor substances such as esters, ketones, alcohols, phenols, hydrocarbons, and aldehydes in the tobacco flavor obtained by fermentation of a tobacco extract by the bacillus velezensis JXQ21 is obviously increased, and the flavor has good compatibility with tobacco, and can soften tobacco smoke and improve the smoking taste of cigarettes.