A hinge assembly (10) includes a shaft (12), a follower (16), and a driving means. The shaft has a screw portion (122) defined thereon. The follower has a screw hole (164) defined therein. The screw hole engages with the screw portion of the shaft. The driving means is configured for providing a driving force which makes the follower rotate relative to the shaft. The hinge assembly has only three main components, and occupies a relatively small volume. Accordingly, the space required in an application such as a mobile phone is reduced. In addition, that the engagement of the screw portion and the screw hole of the follower can dampen the opening action of the flip cover, thus protecting the flip cover from damage.