Speed change mechanism and automatic gearbox

The utility model provides a speed change mechanism and automatic gearbox, wherein speed change mechanism includes the input shaft, the jackshaft, the output shaft, two at least profile modified gear are vice, with at least two gear one -to -ones, vice first gear and the second gear of including of every profile modified gear, first gear setting is on the jackshaft, and the second gear sets up on the output shaft, or the second gear sets up on input shaft and output shaft, two at least synchronous wares set up on the output shaft, and two at least synchronous wares can mesh mutually with the second gear and carry out the gear that corresponds, wherein, two at least gears are equipped with by the low gear number of arranging in proper order to the height, and the corresponding second gear of two at least gears that is equipped with adjacent gear number can mesh with different synchronous wares mutually. The utility model provides a speed change mechanism when the gear shift of adjacent gear number, has reduced