As an effective analgesic, opioid analgesics are widely used in the treatment of moderate to severe pain. However, it is well known that the analgesic effects of opioids vary greatly among different individuals, and effective pain treatment is hindered by huge individual differences. Although these differences in opioid demand are attributed to various factors, the rapid development of genetic factors and pharmacogenomics has made them more and more relevant to the use of opioids. This article reviews the relationship between the demand for opioid analgesics and genetic polymorphisms. Individualized pain treatments have begun to use prediction formulas based on related gene polymorphisms. With the further expansion of scientific knowledge in the future, individualized pain treatment is expected to be greatly improved.