Tear of pectoralis major muscle is a rare sports injury. Patisser [1] first reported tear of pectoralis major in 1822. With the increase of sports population and fitness enthusiasts, reports of tear of pectoralis major muscle have gradually increased [2, 3]. Tear of pectoralis major muscle usually occurs in young males weightlifting (bench press) or horizontal bar exercises and is generally treated conservatively as soft tissue injury, and some are treated with open surgery [4–6]. Tear of pectoralis major muscle is often neglected, and once becomes an old injury, it will increase the difficulty of diagnosis and treatment and affect the curative effect. In our department, three patients with chronic tear of pectoralis major were treated by ultrasonography and magnetic resonance imaging, and minimally invasive surgery with the assistance of arthroscope.