The invention discloses a speed changer gear shifting device, and relates to the technical field of automobile manufacturing. The speed changer gear shifting device comprises a gear shifting cam arranged in a cover shell through a gear selecting and shifting shaft, and the gear selecting and shifting shaft is provided with a gear shifting rocker and a gear shifting stirring head. The gear shiftingcam is provided with an arc limiting groove, and the cover shell is provided with a gear shifting positioning pin. The gear shifting stirring head is movably connected with a gear shifting shift fork. The gear shifting shift fork is provided with a stirring block with a groove. The gear shifting stirring head is provided with a protruding block abutting against the two side walls of the groove. The parts, located on the two sides of the arc limiting groove, of the gear shifting cam are provided with slopes correspondingly. The gear shifting stirring head is provided with an inserting port, the groove opening position of the stirring block is oppositely provided with two limiting parts stretching into the inserting port, and the limiting parts are movably in compression joint with the gearselecting and shifting shaft. Compared with the prior art, in the gear shifting stroke, the stirring block and the gear selecting and shifting shaft are matched for limitation, the machining errors of the distance between the two limiting parts of the stirring block and the diameter of the gear selecting and shifting shaft is easily controlled within the small tolerance range, the gear shifting stroke limiting tolerance range is greatly narrowed, and gear shifting positioning is accurate.