The invention discloses a protecting device for a carrier roller bearing of a belt conveyor, relates to the technical field of carrier rollers, and solves problems that many carrier roller bearing fixing components are used, the service life is short and the like. A plurality of parallel waterproof and dustproof rings with the equal size are arranged on the inner side of a bearing protecting ring of a polyurethane sealing ring of the protecting device for the carrier roller bearing of the belt conveyor sequentially from outside to inside at equal intervals and are in membrane shapes; and outer sealing claws and inner sealing claws of an inner chamber of a bearing block are square pieces molded on the wall of the inner chamber of the bearing block through mechanical pressing, one end of each square piece is fixed, and the other end of each square piece can be bent by a certain angle. The device is simple in structure, easy to machine, rapid to mount and good in fixing and sealing effect.