A hinge assembly includes a resilient member and two rotary units. Each rotary unit includes a shaft, an outer tube, and an inner tube. The outer tubes are sleeved on the shafts correspondingly. The inner tubes are non-rotatably connected to the shafts and rotatably connected to the outer tubes. The resilient member is positioned between the rotary units, thus causing the inner tubes of the rotary units to resist the outer tubes.