In a method for adjusting a viewing angle of 3D images using an electronic device, the electronic device includes a distance sensor, a camera lens and a 3D display screen. The distance sensor senses a distance between a viewer and the 3D display screen, and the camera lens to capture a digital image of the viewer. The method calculates a viewing angle of the viewer according to the distance and a displacement between the viewer and the 3D display screen, and calculates an angle difference between the viewing angle of the viewer and a viewing angle range of the 3D display screen. The method further adjusts a viewing angle of a 3D image according to the angle difference, and displays the 3D image on the 3D display screen according to the viewing angle of the 3D image.