A bearing structure includes a plurality of wave-shaped grooves and an inner surface. The wave-shaped grooves are formed on the inner surface for receiving a lubricating fluid. Each of the wave-shaped grooves extends along a longitudinal axis of the bearing structure. Each of the wave-shaped grooves includes a first peak section, a second peak section, two first connecting sections, two second connecting sections and a trough section. The two first connecting sections are connected to opposite sides of the first peak section, and the two second connecting sections are connected to opposite sides of the second peak section. The trough section is disposed between the first peak section and the second peak section, and the trough section is connected to one of the first connecting sections and one of the second connecting sections. The first and second peak sections and the trough section have a circular arc structure.