Sun spots are formed after receiving a large amount of ultraviolet radiation in a short period of time and usually occur on the cheeks, which are the main area of high exposure. When UV rays from sunlight hit the skin, they accelerate the activation of epidermal melanocytes and promote the production of large amounts of pigment by the melanocytes. The long-wave UV rays in UV light can penetrate the epidermis into the dermis and promote the activation of a variety of cells in the dermis to produce histamine, 5-hydroxytryptamine, and other activated cytokines. These substances will also accelerate the stimulation of melanin production by melanocytes, thus gradually forming pigmented spots on the epidermis and dermis of the face. The severity of sun spots is closely related to the dose of ultraviolet radiation, the duration of exposure and the skin quality of one’s own skin, and even racial and individual differences. Some people form sun spots quickly after sun exposure, while some people with fair skin are less likely to form pigmented spots. Therefore, the best way to prevent pigmentation is to protect yourself from the sun. The formation of sun spots is related to the exposure to ultraviolet rays, and repair after sun exposure also plays a big role in the formation of sun spots. If you actively calm and soothe after sun exposure, repair the skin’s barrier function, and use skin care products with whitening properties, you will reduce the formation of sun spots. For a large number of diffuse sun spots, you can use fruit acid peel type of medical treatment, the treatment can quickly accelerate the metabolism of melanin cells, promote epidermal renewal, play a lightening of pigmentation, whitening effect. For scattered and deeper sun spots, laser or photon with selective photothermal effect can be used to treat. For localized sun spots, when choosing laser treatment and photon treatment, it is recommended to take sufficient rest after sunbathing and wait for the red spots after sunbathing to recover completely before treatment by medical and aesthetic means.