The invention discloses a wind turbine generator system and a bearing component thereof. The bearing component comprises a first bearing, a connecting shaft and a second bearing which are sequentiallyconnected and is characterized in that the first bearing is formed by a first inner ring and a first outer ring which are coaxially coordinated, the outer wall of the first inner ring is provided with a first boss along the circumferential direction, the inner wall of the first outer ring is correspondingly provided with a first groove along the circumferential direction, the first boss is embedded into the first groove, and rolling parts are arranged in gaps between the first boss and the first groove. The bearing component has the advantages that unnecessary bending moment and axial force borne by a blade is consumed as much as possible, the unnecessary bending moment and axial force is not transmitted to a transmission shaft, the load of the transmission shaft is prevented from being increased, the length and diameter of the transmission shaft can be reduced greatly, and space occupation and overall weight can be reduced favorably.