Objective To explore the associations of the polymorphism of μ ⁃ opioid receptor gene （OPRM1）with pain sensitivity and opioid dosage in patients with postherpetic neuralgia（PHN）. Methods The clinical data of 170 herpes zoster（HZ）patients who visited the pain clinic of our hospital from January 2019 to July 2022 were reviewed，90 of them put in the PHN group and 80 put in the non⁃PHN group according to the pres⁃ence or absence of postherpetic neuralgia 3 months after HZ onset. The factors influencing the occurrence of PHN were analyzed by Logistic regression analysis. The two groups were compared in terms of 48h opioid dosage，sleep quality score and state trait anxiety score among different genotypes of PHN patients with moderate and severe pains. #The independent risk factors for PHN were found to include initial treatment > 72 hours，severe pain in acute stage and genotype GG. The frequency of GG genotype distribution was significantly increased across the PHN mild pain，moderate pain and severe pain groups. As compared with the PHN moderate group，the 48 h dos⁃age of opioids in the patients with different genotypes in the PHN moderate and severe pain group were significantly increased（P < 0.05），with the highest in the GG genotype patients. Conclusion The independent risk factors for PHN are initial treatment >72 h，acute severe pain and genotype GG. The polymorphism of OPRM1 gene is the genetic factor that causes individual differences of opioid pharmacodynamics in PHN patients.