A hinge assembly adapted to an electronic device having a casing and a back plate, comprising: a fixing member fixed to the casing of the electronic device and including a side plate and two fixing plates, wherein the two fixing plates extend along a direction from two end portions of the side plate, respectively, and a curved guide rail is formed at the side plate; a sliding shaft passing through and sliding within the curved guide rail of the side plate and including a first torsion device, wherein the first torsion device includes at least one elastic sheet and at least one nut, and the first torsion device provides a first torsion force to the sliding shaft; a connecting member, wherein the sliding shaft passes through one end of the connecting member; a rotating shaft passing through another end of the connecting member and including a second torsion device, wherein the second torsion device includes at least one elastic sheet and at least one nut, the second torsion device provides a second torsion force to the rotating shaft and the first torsion force is less than the second torsion force; and a rotating member fixed to the back plate of the electronic device, wherein the rotating shaft passes through the rotating member; wherein when the sliding shaft is located at a first position and a force applies on the rotating member to make the rotating member rotate toward the first position, the sliding shaft moves from the first position to a second position along the curved guide rail, when the sliding shaft is located at the second position of the curved guide rail and the force applies on the rotating member continuously, the rotating member rotates around the rotating shaft. a fixing member fixed to the casing of the electronic device and including a side plate and two fixing plates, wherein the two fixing plates extend along a direction from two end portions of the side plate, respectively, and a curved guide rail is formed at the side plate; a sliding shaft passing through and sliding within the curved guide rail of the side plate and including a first torsion device, wherein the first torsion device includes at least one elastic sheet and at least one nut, and the first torsion device provides a first torsion force to the sliding shaft; a connecting member, wherein the sliding shaft passes through one end of the connecting member; a rotating shaft passing through another end of the connecting member and including a second torsion device, wherein the second torsion device includes at least one elastic sheet and at least one nut, the second torsion device provides a second torsion force to the rotating shaft and the first torsion force is less than the second torsion force; and a rotating member fixed to the back plate of the electronic device, wherein the rotating shaft passes through the rotating member; wherein when the sliding shaft is located at a first position and a force applies on the rotating member to make the rotating member rotate toward the first position, the sliding shaft moves from the first position to a second position along the curved guide rail, when the sliding shaft is located at the second position of the curved guide rail and the force applies on the rotating member continuously, the rotating member rotates around the rotating shaft.