A method of industrial production for trehalose by way of microbial fermentation comprises the steps of fermentation of trehalose hydrolase and trehalose synthase, starch liquefaction, catalytic reaction, glycosylation, decolorization and filtration, ion exchange, concentration, crystallization, centrifugation, drying, and membrane separation. The method of industrial production for trehalose by way of microbial fermentation has the following advantages: 1, starch is used as the raw material in the method to produce the trehalose through enzymatic catalysis, allowing mass and cheap industrial production of the trehalose; 2, high activity and low dosage of enzymes cause reduction of the production cost; 3, a centrifuged trehalose mother liquor is subjected to membrane separation such that the content of the trehalose is increased, and blending crystallization may be implemented to further increase the yield of the trehalose; 4, an innovative trehalose crystallization process causes the content of the trehalose to be above 50%, the content of glucose to be below 20%, and the content of the one-time crystallization product of the trehalose to be above 98.5%; 5, compared with a process of transforming the trehalose by using maltose, the method has great advantages, such as higher yield and lower production cost.