The invention provides a part positioning device which is used for maintaining a part to be in a first to-be-processed state or a second to-be-processed state; the part comprises a first to-be-processed part and a second to-be-processed part integrally formed; the first to-be-processed part and the second to-be-processed part are matched to form a forming structure; the first to-be-processed partis provided with an annular wall part; and the part positioning device comprises a base, a positioning plate arranged on the base, a first positioning mechanism detachably arranged on the first arranging area of the positioning plate, and a plurality of second positioning mechanisms arranged on the second arranging area of the positioning plate. The part positioning device can maintain the part tobe in different to-be-processed states.