The invention discloses a core rotor device of an exhaust gas turbocharger, which comprises an intermediate shell, a thrust sleeve, a thrust bearing, an oil baffle, and a shaft seal. It has a chamber, and a sealing ring seat is arranged in the chamber, and the sealing ring seat includes a ring member sealed with the inner wall of the chamber, and a ring for dynamic sealing with the shaft seal arranged on the turbine shaft, the ring member, the sleeve The rings are fixedly connected with a ring-shaped connecting piece, and the side of the ring-shaped connecting piece facing the impeller has an arc-shaped end face corresponding to the shape of the impeller. The original connecting disc and the middle shell are changed into the middle shell and the sealing ring sleeve. The larger connecting plate is canceled to avoid product deformation, the original convex seal is changed to groove seal, the oil return space of the product is increased, and the screw compression is changed to the elastic retaining ring compression. The above measures The assembly is convenient, the automatic assembly line is easy to adopt, and the product cost is reduced.