The invention discloses a planet rolling bearing system for supporting a large disc and the rotation of a large disc gear on a circular knitting machine, which is characterized by adopting two groups of conventional rolling bearings evenly distributed and arranged on the large disc as planets, wherein one group of the conventional rolling bearings support the end face of the large disc gear, while the other group supports the central hole of the large disc gear. As shown by an attached drawing of the abstract, the planet rolling bearing system comprises the large disc gear 1, the large disc 2, a horizontal bearing block 3, a rolling bearing 4, a shaft elastic damping ring 5, a hexagon socket head cap screw 6, a rolling bearing 7, a shaft damping ring 8, an O-shaped rubber sealing ring 9, an eccentric bearing block 10, a hexagon socket head cap screw 11 and a gasket 12. By comparing the planet rolling bearing system with the prior steel wire track rolling bearing and the prior friction plate sliding bearing, the planet rolling bearing system has the following obvious advantages that: (1) the running precision of the circular knitting machine is higher; (2) the running is more flexible; (3) the service life is longer; (4) the production cost of the circular knitting machine is greatly reduced; (5) the maintenance is more convenient; and (6) the circular knitting machine which is scrapped and cannot be required due to the abrasions of mounting parts of the large disc gear and the large disc steel wire track can be repaired completely, and the circular knitting machine which is obsolete because a wear-resistant piece sliding bearing cannot be repaired due to the abrasions of a central hole of the large disc gear and a central shaft of the large disc gear can be completely repaired.