Acne is a multifactorial disease whose onset is mainly related to sex hormone levels, heavy secretion of sebaceous glands, proliferation of Propionibacterium acnes, abnormal keratinization of follicular sebaceous ducts, and inflammation. The principles of treatment are lipid removal, keratinolysis, antiseptic, anti-inflammatory and regulation of hormone levels. Topical medications include treatment with retinoids, and also topical antibiotics for anti-microbial treatment, such as lincomycin, benzoyl peroxide, etc. For moderate to severe acne, oral antibiotics can be combined with macrolide antibiotics to control inflammation, and retinoids can be taken for severe acne. Other treatments such as red and blue light have anti-inflammatory and antibacterial effects and are more efficient for mild to moderate acne. Photodynamic therapy can shrink sebaceous glands, kill Propionibacterium acnes, and anti-inflammatory, etc. It has the effect of preventing recurrence and is a better choice for the treatment of moderate to severe acne. The after-effects of acne mainly include hyperpigmentation and scars. Hyperpigmentation can be removed using photorejuvenation, and scars can be reconstructed by fractional laser for skin reconstruction.