The utility model discloses a peripheral gear -rack transmission mechanism of seat elevator, include the support rail who follows stair railing and arrange, the support rail side is provided with therack, and a rail bearing who connects the seat is installed to the top, be provided with on the rack rather than the meshed gears, the motor drive of gear on by the seat. The utility model provides aperipheral gear -rack transmission mechanism, the use be directional motion's on horizontal plane rack and pinion, mesh through parallel gear, make it also can turn in narrow department, better utilization to the meshing space restriction vertical face less relatively. The utility model discloses it is bigger on parallel regional tooth mesh effect plane, can let non -parallel gear engagement havea bigger turning radius, so the wearing and tearing influence that is brought by the gear will be dropped to minimumly.