This paper summarizes Professor Chen Hongfeng’s experience in treating complex mastitis with acne based on quadruple external treatments,including incision and expansion- thread dragging- fumigation and washing- cotton pad. It is considered that this disease is caused by qi stagnation and blood coagulation,obstruction of meridians and collaterals,which leads to chronic stagnation transforming into heat. The heat induces the rotten skin and then it becomes abscess and easily forms fistula after fester. According to the different stages of the disease,the quadruple comprehensive treatments of “incision and expansion- thread dragging- fumigation and washing- cotton pad” can be applied. The application period,methods and attentions of each therapy are introduced. One proven case is presented.