A hinge assembly includes a pivot shaft, a first supporting member, a second supporting member, a first positioning piece, and a second positioning piece. The first supporting member and the second supporting member are sleeved on the pivot shaft. One of the first supporting member and the second supporting member is non-rotatably connected to the pivot shaft. The first positioning piece and the second positioning piece are sleeved on the pivot shaft, and adjacent to each other. The first positioning piece defines a plurality of positioning protrusions. The second positioning piece defines a plurality of positioning holes for receiving the positioning protrusions. The second positioning piece is elastic. When the first supporting member rotates relative to second supporting member, the second positioning piece deforms.