Acne, commonly known as “pimples”, is a chronic inflammatory disease of the skin characterized by scattered pimples, papules, pustules, nodules and cysts. Acne is a chronic inflammatory disease of the skin, mostly in young men and women, with a prolonged and recurrent course, causing great inconvenience to patients’ lives, studies and work. The most basic pathogenesis of acne is the following four aspects: 1) excessive sebum secretion; 2) hyperkeratosis of follicular sebaceous ducts; 3) overgrowth of Propionibacterium acnes; 4) inflammation, immune response, etc. Propionibacterium acnes can be killed by blue light, so the use of blue light for acne treatment is a relatively new method with significant efficacy and few side effects.