The invention aims at providing a bearing and an inner ring thereof. By improving the structure of the inner ring, the number of parts forming lubricating oil delivery channels of the bearing can be reduced, the possibility of lubricating oil contamination and leakage is lowered, and meanwhile the bearing is evenly lubricated and cooled. The inner ring of the bearing is provided with a circle of locating flanges formed on the inner circumferential side of the inner ring, the multiple axial oil delivery channels and an oil gathering ring. The oil gathering ring is located at the end side of the inner ring of the bearing. The locating flanges are located on the inner position in the axial direction relative to the oil gathering ring. The locating flanges protrude in the radial direction from the inner circumferential wall face of the inner ring of the bearing. The oil delivery channels penetrate the locating flanges in the axial direction from the oil gathering ring on the inner circumferential wall face. Oil injection holes are formed in different positions of the oil delivery channels and penetrate the inner ring of the bearing from the inner circumferential side wall face. The oil delivery channels and the oil injection holes are used for lubricating and cooling a bearing track, a holding frame and a rolling body, wherein the holding frame and the rolling body are arranged on the peripheral side of the bearing track.