The invention provides a compound enzyme rich in beta-mannase as well as preparation and application thereof. The cultured fermentation product contains beta-mannase, beta-glucanase, acidic protease,xylanase, pectinase and alpha-galactosidase. Aspergillus niger is named as Aspergillus niger BAK200310, and the preservation number is CGMCC No. 19616. The fermented compound enzyme is extremely richin zymoprotein types, contains various zymoprotein components, and almost covers all components in conventional enzymes; different enzymes perform respective functions, and different components of onesame enzyme cooperate with each other to jointly exert a greater enzymatic hydrolysis effect. The compound enzyme is rich beta-mannase and complete in enzyme components, and the enzyme activity of the compound enzyme can reach 12170U/g according to national standard detection.