A head worn displaying device of the disclosure includes an optical reflective lens, a display screen and a cover. The optical lens and the display screen are mounted under the cover, and the cover may be similar to a hat tongue located ahead of the forehead of a user. The display screen can be integrated in a mobile phone, and a holder such as a clamper set is used to clamp the mobile phone. The angle of the optical lens can be adjusted, for example, by using a sliding groove and a magnetic hinge which are located at a front end of the hat tongue. The magnetic hinge slides in the sliding groove to adjust a distance between the display screen and the optical lens. The light rays of the display screen will be reflected by the optical lens to form virtual magnified images with reduced distortions for both eyes at the same time, and the optical lens optically combines the reflected virtual images with and external environmental light rays transmitted through the optical lens to form the augmented reality for the eyes.