The invention discloses a rigid internal mold of a tire vulcanizing machine and relates to the field of tire vulcanizing equipment. The rigid internal mold of the tire vulcanizing machine is high in vulcanizing pressure and swelling-shrinkage degree, suitable for tires of all types and capable of remarkably improving the vulcanizing efficiency. The rigid internal mold of the tire vulcanizing machine comprises a swelling-shrinkage device and a transmission device for driving the swelling-shrinkage device. The swelling-shrinkage device comprises a drum which is used for tire shaping after swelling. The drum is formed by splicing first inner mold pads and second inner mold pads alternately. A sleeve shaft assembly connected with the transmission device is arranged in the center of the drum and comprises a mandrel located in the center and an outer shaft, and the mandrel is sleeved with the outer shaft. A plurality of first fixing plates which penetrate through the outer shaft and correspond to the first inner mold pads are arranged on the mandrel in the circumferential direction. A plurality of second fixing plates corresponding to the second inner mold pads are arranged on the outer shaft in the circumferential direction. The ends, away from the sleeve shaft assembly, of the first fixing plates and the second fixing plates are provided with protrusions. The first inner mold pads and the second inner mold pads are fixedly connected with clamping grooves used for clamping the protrusions.