Objective To investigate the perioperative analgesic effect of serratus anterior muscle plane block combined with transverse thoracic muscle block under ultrasound guidance in modified radical mastectomy and its effect on early postoperative recovery. Methods 105 patients with elective modified radical mastectomy were selected and randomly divided into general anesthesia group (group G), serratus anterior plane block group (group S), serratus anterior plane combined with transverse thoracic muscle block group (ST group). The serratus anterior plane block or transverse thoracic muscle block was performed before anesthesia induction in group S and group ST. The QoR15 recovery quality scores were recorded before and 24 h after surgery. Patients mean arterial pressure (MAP) and heart rate (HR) were recorded at room admission (T0), before skin incision (T1), skin incision (T2), medial breast operation (T3), and 5min after extubation (T4) . The amount of propofol and remifentanil during the operation was recorded. The visual analogue scores (VAS) at 30min after extubation (T5), 2h (T6), 4h (T7), 8h (T8), 12h (T9), and 24h (T10) after operation were evaluated. The number of postoperative analgesia and the incidence of complications were recorded. Results The total QoR15 score, pain score, physiological comfort score, and emotional score of the S group and the ST group were higher than those of the G group at 24h (P＜0.05). The total QoR15 score, pain score, physiology and comfort score at 24h after operation in the ST group was higher than that of group S (P＜0.05). The MAP and HR of patients in group ST at T2, T3, and T4 were lower than those of group G and S (P＜0.05). The amounts of propofol and remifentanil in the S and ST groups were lower than those in the G group (P＜0.05). The dosage of remifentanil in the ST group was lower than that in the S group (P＜0.05). There was no significant difference in the amount of propofol (P＞0.05). The VAS scores were lower within 24 hours after surgery in the S group and the ST group compared with group G (P＜0.05). The ST group was lower than the S group at the T6T9 time point (P＜0.05). The number of postoperativeanalgesia and the incidence of dizziness was lower in the S and ST groups than in the G group (P＜0.05), but there was no significant difference between the two groups (P＞005. There was no significant difference in the incidence of postoperative nausea and vomiting in the three groups(P＞0.05).〖WTHZ〗Conclusion For patients with modified radical mastectomy, the analgesic effect of the serratus anterior plane block combined with the transverse thoracic muscle plane block is more complete during the perioperative period, which not only can significantly reduce the amount of perioperative analgesics,but aslo reduce the incidence of dizziness and improves patients' early recovery quality.