The invention relates to a sealing structure capable of achieving bearing cavity-sharing and bearing external cavity pressure equalizing. The sealing structure is provided with front and rear bearing supporting points, one of the bearing supporting points is designed by adopting a simple supporting structure, the other one of the bearing supporting points is designed by adopting a cantilever supporting structure, so that two adjacent bearings are close in space, a front bearing seat and a rear bearing seat are connected together, the cavity-sharing design between the adjacent bearings is achieved, and thus pressure in a bearing cavity is convenient to adjust. A plurality of air hole structures are arranged on the front bearing seat and the rear bearing seat in the circumferential direction correspondingly, the angular positions, the shapes and the sizes of the air hole structures on the two bearing seats are mutually matched, and the air hole structures on the two bearing seats correspond one to one, channels communicating with two bearing external cavities are formed, and therefore pressure equalizing of the front bearing external cavity and the rear bearing external cavity is achieved; flow path of an air system is simplified, the design difficulty of the air system sealing the bearing cavity is reduced, and moreover the reliability of operating is high; and pressure of the bearing external cavities is adjusted by adjusting comb tooth gaps of inlet-outlet ports, build-up of the pressure of the bearing external cavities is facilitated, and the sealing effect is enhanced.