A small round hard object on the left side of the chin can be considered as a boil, flat wart or sebaceous cyst and other skin lesions. 1. Boil: It can be triggered by Staphylococcus aureus, leading to suppurative inflammation of the hair follicle and surrounding tissues. It starts as a follicular inflammatory papule and progresses to form a hard nodule with redness, swelling and hot pain, and a punctate pus plug can be seen at the top. 2. Warts: After facial skin is infected with human papillomavirus, round, hard, rice grain to soybean-sized raised papules may appear, with a rough surface, and may be solitary. 3. Sebaceous cysts: when the sebaceous ducts in the chin area are blocked, there is sebaceous gland stagnation, which can form a round, hard pimple, and white secretion can appear after squeezing. It is recommended that patients with unexplained round, hard skin lesions on the chin, timely medical treatment, standardized treatment under the guidance of the doctor, so as to avoid delays in the condition, bringing adverse effects on the body.