Acne marks on the back are depressed scars that remain after acne heals. Currently, there are various methods to treat these depressed scars, including chemical peeling and physical therapy. 1. Chemical peeling: By applying chemical peeling agents such as salicylic acid and fruit acid on the lesions, the stratum corneum will be peeled off and gradually replaced by new epidermis, which will improve the appearance of the skin texture; at the same time, it can also stimulate the regeneration of the deep collagen, which will improve the persistence of depressed scarring. 2. Physical therapy: Physical methods such as radiofrequency therapy, fractional laser, intense pulsed light and other physical methods have a therapeutic effect on depressed scarring and can be used to remove acne marks behind. Patients who are willing to be treated need to go to a regular medical institution to choose the appropriate treatment method after a professional doctor’s interview.