The invention discloses a novel planet wheel assembly transmission mechanism. The novel planet wheel assembly transmission mechanism includes a planet shaft. A bearing inner race is arranged on the outer diameter position of the planet shaft, and the planet shaft is in interference fit with the bearing inner race. A groove is formed in the working surface of the bearing inner race, and a ball is arranged on the groove and makes contact with the groove of the bearing inner race and a planet gear inner ring respectively. A hole circlip is arranged in a deep groove of an inner hole of a planet gear. The inner hole of the planet gear is further provided with a pair of inner check rings, and the section of each inner check ring is of an L-shaped structure. The hole circlip is covered with the inner check rings, and the inner ring bodies of the inner check rings make contact with the end face of the bearing inner race. The left end and the right end of the bearing inner race are provided with a pair of outer check rings, one end of each outer check ring makes contact with the end face of a bearing inner check ring, and the other end of each outer check ring is blocked through a planet carrier. The novel planet wheel assembly transmission mechanism is convenient to assemble, reliable and high in accuracy.