The utility model relates to a walnut cake grinding and protein extracting tank, and belongs to the technical field of mechanical design and manufacturing. The extraction tank comprises a tank body, acolloid mill and a circulating pipeline, a feeding groove and an alkali liquor pool are arranged at the top of the tank body; a first valve is arranged between the feeding groove and the tank body, and a second valve is arranged between the feeding groove and the alkali liquor pool; a discharge port of the tank body is connected with a feed port of the colloid mill through a pipeline; a dischargeport of the colloid mill is respectively connected with the discharge pipe and the circulating pipeline, and a three-way valve is arranged at the joint; the other end of the discharge pipe is connected with the upper part of the tank body. The extraction tank is reasonable in structural design and small in occupied area, achieves rapid dissolution of protein in walnut cakes, dissolves the proteinwhile grinding, and has efficient extraction performance.