The invention discloses a method for preparing walnut protein fermented soybean milk, and relates to the technical field of fermented milk product production. The method comprises the nine operation steps of drying and milling, mixing, blending, homogenization and degassing, sterilization and cooling, inoculation fermentation, secondary inoculation, filling fermentation and cooling after-cooking.By means of the method, puffed walnut meal is utilized for providing plant protein; on one hand, the situation that the fermentation of strains is influenced by excessive oil in walnut powder is avoided, and the use of an emulsifier is also reduced; on the other hand, the puffed walnut meal can provide a better mouthfeel; meanwhile, multiple strains are utilized for secondary fermentation, nutrients are more abundant, and a unique flavor is brought.