A cushioning air bag with automatically adjustable clamping pressure includes an air cylinder sheet and an adjustable air sac sheet, where the air cylinder sheet includes a first air valve and a plurality of air cylinders, one end of the first air valve is positioned in the plurality of air cylinders, and an adjustable air sac sheet, includes a plurality of cushioning adjustment zones attached to wall surfaces of the plurality of air cylinders, a bag is formed when the air cylinder sheet and adjustable air sac sheet are filled with air, an accepting space is included among the plurality of cushioning zones positioned in the bag, used for clamping a different size of object when the object is received in the accepting space.