The invention especially relates to a dyeing accelerant for printing and dyeing of a silk-cotton blended fabric and a preparation method thereof, belonging to the technical field of textile assistants. The dyeing accelerant for printing and dyeing of the silk-cotton blended fabric exerts good dyeing effect on the silk-cotton blended fabric, is uniform in dyeing, good in dyeing retarding performance and high in fastness to soaping, and the dyed silk-cotton blended fabric is free of point-defect phenomena like color strips and color spots; the dyeing accelerant is simple, reasonable and scientific in composition, low in the cost for raw materials, friendly to environment, natural, and free of pollution, and poses no toxicity to human beings; chitin is applied to an acidic dye, so excellent level dyeing effect is obtained during dyeing of wool, and the fabric is endowed with good antibacterial properties at the same time; tea extract is used in the dyeing accelerant, and since the tea extract is rich in tea polyphenol and flavonoids, the antibacterial and insect-preventing properties of the dyed fabric can be further improved; montmorillonite is a natural mineral and is friendly to environment and free of pollution; and the preparation method is simple in process, low in cost, free of toxic and pollution and friendly to environment.