An electronic device has a method capable of automatically executing angle rotation. A second body is rotatably connected to a first body of the electronic device. A hinge mechanism is disposed between the first body and the second body. The hinge mechanism includes a hinge component, a motor unit, a coupling component and an angle detecting unit. The first body and the second body are connected to the hinge component. The motor unit is electrically connected to a controller of the electronic device. The coupling component is connected between the hinge component and the motor unit. The angle detecting unit is connected to the hinge component or the coupling component to read its rotary angle. The controller drives the motor unit to rotate the hinge component via the coupling component, and the second body can be moved relative to the first body and be fixed at a predetermined position.