A hydrodynamic bearing assembly comprises a bearing (10) defining a bearing hole (12) therein, a shaft (20) rotatably received in the bearing hole with a bearing clearance formed between a bearing surface of the bearing and an outer surface of the shaft, and a cover (40) attached to a top end of the bearing. The bearing clearance is filled with lubricant. A locking groove (22) is formed in an outer periphery of the shaft. The cover defines a through hole (42) receiving the shaft at the locking groove. Interlocking devices are formed on the cover and the bearing to join the cover and the bearing.