The invention discloses a hot forging forming die for airplane upper rafter plate rib pieces. The hot forging forming die comprises an upper die and a lower die. The die closing surface of the lower die is provided with a lower cavity. A forging cavity matched with the airplane upper rafter plate rib pieces in shape is formed between the lower end face of the upper die and the upper end face of the lower die after die closing. The bottom surface of the lower cavity is provided with a rib groove which is through in the length direction, and the rib groove is matched with the protruding parts of the airplane upper rafter plate rib pieces in shape. The rib groove divides the bottom surface of the lower cavity into two parts in the width direction, and the two parts in the width direction of the bottom surface of the lower cavity are each provided with a plurality of resistance grooves in the length direction. The resistance grooves are used for preventing metal blanks from flowing to the two ends, in the length direction, of the lower cavity in the forming process of the plate rib pieces. By adopting the die for manufacturing airplane upper rafters, the filling effect of the rib parts of the airplane upper rafters is better, the length of the fully-filled portions of the rib parts is increased by 40%-50% compared with airplane upper rafters produced by a die without resistance grooves, forming quality requirements are met, and it is unnecessary to increase the subsequent machining allowance.