The present disclosure provides a closure driving mechanism and a medical stapler including the same. The closure driving mechanism includes a driving part and a cylinder body, the driving part is connected with a closure pulling sheet of the stapler, and a cavity provided with a one-way valve is formed inside the cylinder body. When the driving part moves toward a distal side of the stapler, a volume of the cavity is decreased, the one-way valve is closed, and the driving part drives the closure pulling sheet to move distally, so as to open a head assembly of the stapler. Since the driving part is subjected to a resistance of compressed air in the cavity, a movement speed of the driving part is decreased, and the head assembly is opened slowly to prevent a force of opening the head assembly being too large to damage surrounding tissues.