The invention discloses a preparation method for a sandwich doughnut cake, and belongs to the field of preparation of doughnut cakes. The sandwich doughnut cake is prepared from the following raw materials in parts by mass: 22-23 parts of medium-strength wheat flour, 19-22 parts of white granulated sugar, 4-6 parts of water, 18-21 parts of refined vegetable oil, 25-26 parts of fresh eggs, 5-6 parts of corn starch, 1-2 parts of edible salts, 0.5-0.8 part of double-effect baking powder, 0.1-0.2 part of citric acid, 0.05-0.15 part of edible flavor, 2-6 parts of Custard cream, 5-6 parts of coating chocolate, 0.2-0.5 part of chocolate cream, 0.04-0.06 part of a d-sorbitol solution, 0.04-0.05 part of glycerol, 0.04-0.05 part of xanthan gum and 0.10-0.15 part of a cake emulsifier. A preparation method for the sandwich doughnut cake comprises the following steps: preparing the raw materials and mixing the raw materials, fermenting flour pulp, slip-casting and molding the fermented flour pulp, roasting the fermented flour pulp, carrying out core casting on the roasted flour pulp, de-molding and cooling the flour pulp to obtain a cake, forming patterns on the coating of the cake, and packaging and warehousing the cake. The preparation method further comprises preparing coating chocolate. The sandwich doughnut cake adopts various formulas, and is rich in nutrient, is fine in classifying in a preparing process, steps are smooth, and the operation is easier.