The utility model relates to a car seat shoulder rest adjustment mechanism, including controing subassembly and adjusting part, it includes pivot, two initiative conical gear, the 2nd reducing gear, motor to handle the subassembly, the pivot transversely sets up, and two initiative conical gear fix the cover respectively and establish at the both ends of pivot, and the rigid coupling has the 2nd reducing gear in the pivot in one of them initiative conical gear outside, the 2nd reducing gear is through driving with the meshing of the epaxial reducing gear of motor output, all the cooperation is equipped with the adjusting part on two initiative conical gear, and two sets of adjusting parts are symmetry setting, the adjusting part includes driven conical gear, connecting rod, backup plate and regulating plate, driven conical gear and the meshing of initiative conical gear, the perpendicular rigid coupling of connecting rod is on driven conical gear, the one end and the connecting rod rigid coupling of regulating plate, the other end swing joint of regulating plate has the backup plate, the utility model discloses it is convenient to adjust, adapts to the crowd of the different bodily forms and shoulder width, has improved car seat's comfort level.