An automatic lifting mechanism for motorcycle saddle mainly includes a first and a second supporting arm respectively fixed to a saddle and a body of a motorcycle, at least one spiral spring having two sideward extended terminal ends separately pressed against the two supporting arms, and a damping device located in the at least one spiral spring to rotatably engage at two ends with the two supporting arms. While a spring force of each spiral spring quickly elastically stretches open the first and the second supporting arm when the saddle is unlocked, the damping device limits a rotating speed of the two supporting arms, so that the saddle could be automatically lifted or moved downward at a buffered speed without the risk of injuring a user.