The invention belongs to the field of sand mold casting, and relates to a sand mold casting die plate, in particular to a self-locating die plate of a sand mold. The self-locating die plate of the sand mold comprises an upper die plate body and a lower die plate body arranged on the lower portion of the upper die plate body. First trapezoidal grooves are formed in the middle of the upper die plate body. Second trapezoidal grooves are formed in the middle of the lower die plate body. The first trapezoidal grooves are the same as the second trapezoidal grooves in size and structure. Upper mold bags protruding upwards are arranged in the middles of the first trapezoidal grooves. Lower mold bags which are recessed downwards and matched with the upper mold bags are arranged in the middles of the second trapezoidal grooves. Each trapezoidal groove is an isosceles trapezoid, and the locating inclination angle of each isosceles trapezoid ranges from 5 degrees to 40 degrees. The self-locating die plate of the sand mold has the beneficial effects of being simple in structure, precise in location, high in practicability, easy to manufacture and the like, the length of the mold thickness is increased after flat parting is transformed into curved surface parting, and the phenomenon of bleeding from parting is reduced.