Wood’s lamp is a commonly used examination equipment in dermatology, which irradiates the patient’s skin in a dark room environment and determines different skin diseases by showing different colors of fluorescence, and the results of the Wood’s lamp are best judged by a professional dermatologist. The bright blue-white fluorescence under Wood’s lamp may be vitiligo. Pigmentation increasing diseases become more obvious under Wood’s lamp, and the boundary is more clear, such as epidermal melasma with darker color, and dermal melasma with less obvious color change. Wood’s lamp can be used for infectious skin diseases, for example, blue-green fluorescence may be rust-colored microsporidia, light blue fluorescence is a sign of Trichophyton xylanicum, and yellow-green fluorescence is Candida albicans. Acne vulgaris will show brick-red fluorescence under the Wood’s lamp, and red fluorescence may be a specific manifestation of porphyria under the Wood’s lamp.