[Abstract] Objective: To evaluate the safety and feasibility of transversus thoracic muscle plane - pectoral nerves?(TTP-PECS) block in??patients undergoing?modified radical mastectomy under opioid-sparing general anesthesia. Methods: Sixty patients of ASA I or II, aged 34-64 years, weighing 45-73 Kg, scheduled for modified radical mastectomy,were randomly divided into the TTP-PECS block combined with opioid-sparing general anesthesia group (group TO ) and the conventional general anesthesia group ( group GA ),with 30 cases in each group. The SBP, DBP, HR and VAS scores at rest and during movement at different time points of patients in both group were recorded, the QoR-40 scores were assessed at 24 hours after surgery, and the incidence of perioperative adverse reactions in both groups were also observed. Results: Compared with T0 , the SBP, DBP, and HR at time points T1 to T4 were significant decreased(P<0.05), but there were no obviously difference between the group TO and group GA(P>0.05). The VAS scores for both resting and movement pain at 2h, 6h, and 12h after surgery in the group TO were significantly lower than those in the group GA (P<0.05). The total score of the QoR-40 scale at 24h after surgery, as well as the scores for emotional state, physical comfort, psychological support, and pain, were all significantly higher in the group TO than those in the group GA (P<0.05). The incidence of cough reflex during induction and postoperative nausea and vomiting were significantly lower in the group TO than those in the group GA (P<0.05). Conclusions: The combination of? TTP - PECS block and oxycodone - propofol opioid-sparing general anesthesia is a safe and effective approach?for?patients?undergoing?modified radical mastectomy. This anesthesia technique?can provide?enhanced?postoperative?pain?relief and decrease the incidence of postoperative nausea and vomiting, therefore, it can improve the early recovery quality of patients with breast?cancer.