The invention discloses a reinforcing device of a monkey machine for fixing jeans. The reinforcing device comprises an inflating body of the monkey machine. The top of the inflating body of the monkeymachine is fixedly connected to a connecting rod, the bottom of the inflating body of the monkey machine fixedly communicates to two inflating rubber sleeves, and rotary drums are fixedly connected to two sides of the inflating body of the monkey machine. According to the reinforcing device of the monkey machine for fixing jeans, by arranging the fixed rotary drum and matching a slide bar, a threaded bushing, a second limiting block, a first limiting block, movable pipe, a sliding bushing, a rotary cap, a bearing, a stress block, a supporting rod, an outer bushing, a movable rod, a baffle plate, a fixed block, a powerful tension spring, a push plate and a clamping plate, a fixing device is designed on the monkey machine in a targeted manner; by means of the elastic deformation principle of the powerful tension spring and the threaded propelling principle of the movable bushing, the effect of fixing the jeans is achieved further, so that the effect that the jeans which is processed bythe monkey machine does not fall is achieved.