The invention discloses a high-positioning-precision photoetching object lens frame with a replaceable lens, belongs to the technical field of deep ultraviolet projection photoetching object lens structure design, and aims at solving problems in the prior art that a conventional structure is complex, the operation space is large, the positioning and repeated positioning precision is low and the lens is liable to be polluted. An outer lens frame is in a cylindrical structure, and two inner side walls of the outer lens frame are respectively provided with a chute. An inner side wall is provided with a conical groove and a V-shaped groove, and one end, close to an opening, of the upper end face of the interior of the outer lens frame is provided with a ball head A. An inner lens frame is in a square structure, and any two opposite side walls are provided with sliding rails. One side wall, adjacent to the side wall where the sliding rail is located, is provided with two ball heads B. The positions of the two head balls B are respectively opposite to the conical groove and the V-shaped groove. A part, corresponding to the ball head A, of the upper end face of the square structure is provided with an upper platform. The sliding rails of the inner lens frame cooperate with the chutes in the outer lens frame. An outer side of the inner lens frame is provided with a protection cover, and the protection cover is fixedly connected with the outer lens frame through a screw.