An irradiation device comprises a light source, an optical switch element and an image recognition module communicatively connected to the optical switch element. In some embodiments, a contour of a target area is recognized by an image recognition module and is provided by the image recognition module to the optical switch element, and a contour of an irradiation area of the light source is controlled by the optical switch element to match with the contour of the target area according to the contour of the target area provided by the image recognition module. Thus, when skin diseases are treated using the irradiation device according to some embodiments of the present disclosure, the contour of the irradiation area of the light source coincides with the contour of the target area, thereby ensuring a therapeutic effect with respect to the target area while avoiding damages to skin in a healthy area.
