Objective:To investigate the effect of modified thoracic nerve block on postoperative analgesia and early recovery of breast cancer patients after modified radical mastectomy.Methods:Sixty female breast cancer patients who were scheduled to undergo modified radical mastectomy in the Second Hospital of Shanxi Medical University from March 2019 to December 2019 were selected, and the patients were all American Society of Anesthesiologists (ASA) grade Ⅰ-Ⅱ. According to the random number table method, the patients were divided into three groups: improved group [third rib approach serratus anterior plane block (SAPB)+pectoralis major muscle superficial anterior cutaneous branch of intercostal nerve block combined with general anesthesia, STG group], SAPB combined with general anesthesia group (SG group) and general anesthesia+postoperative intravenous controlled analgesia pump group (GP group), with 20 cases in each group. VAS scores at 30 min, 2 h, 4 h, 12 h and 24 h after surgery, 15-item quality of recovery scale (QoR-15) scores at 1 d before and 24 h after surgery, sleep duration on the night after surgery, intraoperative opioid dosage, the time between stop medication and awakening, postoperative flurbiprofen ester dosage, nausea, vomiting, dizziness, puncture site infection, pneumothorax, infection and other adverse reactions were recorded.Results:The VAS scores at 30 min, 2 h, 4 h, 12 h, 24 h in the STG group were lower than those in the SG group and GP group, the VAS scores at 2 h, 12 h and 24 h after surgery in the SG group were lower than those in the GP group, and the differences were statistically significant (all P < 0.05). The QoR-15 score at 24 h in the STG group was higher than that in the SG group and the GP group [(137.85±2.81) points vs. (134.80± 2.72) points, (133.80±5.16) points], and the differences were statistically significant (all P < 0.05). The sleep duration on the night after surgery in the STG group and the SG group was longer than that in the GP group [(6.03±0.90) h, (5.48±1.12) h vs. (3.85±1.76) h], and the differences were statistically significant (all P < 0.05). The intraoperative opioid dosage and the time between stop medication and awakening in the STG group and the SG group were lower than those in the GP group, and the differences were statistically significant (all P < 0.05). The postoperative flurbiprofen ester dosage and the incidence rates of nausea, vomiting and dizziness in the STG group were lower than those in the SG group and the GP group, and the SG group was lower than the GP group, and the differences were statistically significant (all P < 0.05). Conclusion:The modified thoracic nerve block can relieve early postoperative pain, reduce the amount of intraoperative opioids, and improve the quality of patients' early recovery without increasing adverse reactions.