Objective To review the genotypes of OPRM1, CYP3A4*1G, CYP3A4*18B and ABCB1 in children undergoing adenoid tonsillectomy in northwestern China, and to identify the gene mutation rate related to analgesia. Methods From September 2016 to October 2019, 513 children (337 males and 176 females) with adenoid tonsil surgery in Northwest China (Shaanxi, Gansu, Ningxia, Qinghai, Xinjiang) were enrolled in Xijing Hospital. The detection results of OPRM1, CYP3A4*1G, CYP3A4*18B and ABCB1 gene polymorphisms were reviewed. Results The proportion of OPRM1 (118A G) mutant heterozygote AG type was 42.88%, and that of mutant homozygote GG type was 9.55%. The percentages of CC, TT, TC and CT in CYP3A4*1G were 54.58%, 5.09%, 40.35% and 0%, respectively. The proportion of CYP3A4*18B heterozygote AA type and AG type was 99.03% and 0.97%, respectively. The percentages of CC, TT, TC and CT in ABCB1 were 32.49%, 24.34%, 42.69% and 0%, respectively. There was no significant difference in the distribution of genotypes between male and female. Conclusion Three of the four gene loci related to opioids such as fentanyl have a high mutation rate in children undergoing adenoid tonsillectomy in Northwest Han nationality, suggesting that the determination of gene site mutation has important research value in guiding clinical anesthetic use.