Abstract: Objective To investigate the effect of preoperative ultrasound-guided quadratus lumborum block（QLB） on early recovery and T cell immune function in patients undergoing radical gastrectomy. Methods Ｔotals　of 68 patients who underwent radical gastrectomy in our hospital were selected as the study subjects from March 2017 to June 2018，and divided into observation group（n=34） and control group（n=34） according to random number table method. After anesthesia induction，the observation group received color Doppler ultrasound-guided bilateral QLB（ropivacaine hydrochloride injection），while the control group received saline injection only. The postoperative analgesia indexes，VAS scores，serum CD4⁺CD25⁺ T cells level and adverse reactions of the two groups were compared. Results The dosage of sufentanil，the times of pressing analgesic pump and the proportion of remedial analgesia in the observation group were lower than the control group（P<0.05），and the score of analgesic satisfaction was higher than that in the control group（P<0.05）. The VAS scores of resting and moving state at 2，6，12 and 24 h after operation in the observation group were lower than those in the control group（P<0.05）. The difference of CD4⁺CD25⁺ T cells content before and after operation in the observation group was higher than that in the control group（2.0±0.8 vs 1.1±0.6，t=5.248，P＜0.001）. The proportion of nausea and vomiting（5.9% vs 26.5%），and vertigo（2.9% vs 20.6%）after anesthesia in the observation group were lower than those in the control group（P<0.05）. Conclusions Preoperative ultrasound-guided  quadratus lumborum block can reduce the dosage of analgesic drugs in patients undergoing radical gastrectomy，improve the analgesic effect during and after operation，the satisfaction of pain after operation and T cell immune function and with less adverse reactions. 

Key words: Gastric cancer, Ultrasound guidance, Quadratus lumborum block, Radical gastrectomy for gastric cancer, Analgesia