The invention relates to a high-precision framework welding process device which solves the problem that an existing planetary framework electron beam welding combination process is large in deformation. The high-precision framework welding process device comprises a main framework gland, a stepped shaft, an auxiliary framework gland, a stud, a gland nut, a window supporting block and a sliding supporting block, wherein the small end of the stepped shaft extends out of the center of the main framework gland, and the big end of the stepped shaft is fixedly connected with the main framework gland; during using, the main framework gland and the stepped shaft form an integrated assembly to be matched with a main framework of a planetary framework; the auxiliary framework gland is matched with an auxiliary framework of the planetary framework; the stud connects the auxiliary framework gland, the planetary framework and the stepped shaft into a whole; the stud is matched with the gland nut at one end of the auxiliary framework gland; the sliding supporting block is installed on the window supporting block through a wedge-shaped guide rail to form a relatively moving supporting body with the upper face and the lower face being parallel; and the supporting body is installed in a planet wheel installation window formed in the planetary framework. Heat dissipation is rapid in the use process, and the supporting body can effectively prevent welding deformation.