With the incremental trend of benign breast tumor, the surgical process of mastectomy was proceeded too much every day, especially in the Maternal Health Care Hospital, but whether the investigators can find another way to relieve the postoperative pain after such an operation is still unknown. The investigators hypothesized that the pain from the relatively small surgery may not be significant compared to different treatments, even if no drug was delivered to them. The investigators are enrolling patients who underwent mastectomy from benign breast tumor, and are observing the analgesic effects of different drugs.