The utility model relates to a car coupler buffer press mounting machine, which comprises a worktable and a jack, wherein, the jack is mounted on one side of the worktable, and a piston rod of the jack points to the other side of the worktable; a positioning groove arranged at the lower part of a coupler yoke and used for containing and limiting the coupler yoke of the car coupler buffer is formed on a horizontal working plane at the middle section of the worktable; a couple of vertical beams limiting a slave plate of the car coupler buffer and a platform bearing a gib head of the car coupler buffer are arranged on the other side of the worktable; the median plane of the clearance between the vertical beams is fit with the median plane of the positioning groove, and the width of the clearance thereof is in accordance with that of the positioning groove. The car coupler buffer press mounting machine has the advantages of less total area and space of the worktable, convenient and flexile hydraulic operating system, simple press mounting process, wide applicability, capable of alleviating work intensity of workers, and improved manipulation security.