The invention discloses a supporting device used for fruit tree grafting. The device comprises a fixing pile, a fixing base, a first buckle, a fixing hoop, an insertion rod, a bolt, a connecting rod,a hoop, a clamping bolt, sliding grooves, a sliding plate, a second buckle, a fixing plate, a hinge, a spring support, a sleeve, a supporting arm, a supporting rod, a rotary knob, a sliding block, a support, a bayonet lock, and a clamping groove. Beneficial effects of the device are that through arranging the two sliding grooves on the fixing base, and arranging the sliding plate which can slide on the sliding groove in a clamping manner, the sliding plate can be used to slidably adjust positions of the first buckle and the second buckle, the two buckles are ensured to respectively clamp and fix a scion and a stock, so as to ensure connection between the scion and the stock is more stable and firmer, and effectively improve grafting survival rate. Through welding the fixing hoop on the fixing plate, the fixing hoop is used to clamp and wrap a grafting joint, preventing a grafting position from getting wet, and effectively improving airtightness of the joint, and effectively improving grafting success rate.