To analyze the clinical curative effect observation of Modified Longdan Xiegan decoction in the treatment of herpes zoster and its effects on the immune function.Methods:Sixty cases of patients with herpes zoster in our hospital were randomly divided into the control group and the observation group according to Random Number Table, 30 cases in each group. The control group had oral Gabapentin capsule, the observation group had Longdan Xiegan decoction on the basis of treatment of the control group. Changes of simplified McGill pain scores, Oswestry disability index, Hamilton anxiety scale (HAMA) scores, Hamilton depression scale (HAMD) scale score were observed at 1st week and 4th week after treatment. Th17 cell concentration changes before and 4 weeks after the treatment were also meatured.Results: 1) The McGill pain scores were with no statistical differences between the two groups before the treatment (P>0.05), after the treatment. McGill pain scores decreased in the two groups of patients, but the downward trend of the observation group was more obvious; 2) the comparison of the Oswestry disability index were with no statistical differences between the two groups before treatment (P>0.05), after treatment, Oswestry disability index declined in the two groups of patients, the downward trend of observation group was more obvious. 3) HAMA and HAMD negative emotions integral comparison of the two groups were with no statistically significant differences before treatment (P>0.05), HAMA and HAMD negative emotions integral of the two groups were statistical differences before treatment compared to after treatment (P<0.05), the observation group decreased more significantly of HAMA and HAMD negative emotions integral (P<0.05); (4) the human peripheral blood mononuclear cells assay of Th17 were detected in patients of different treatment group by using flow cytometry, the results showed that: Th17 expression of the two groups had no obvious differences before treatment (P>0.05); Th17 cells expression of observation group was obviously lower than the control group1 month after the treatment.Conclusion:Modified Longdan Xiegan decoction can treat herpes zoster effectively, and its mechanism may be related to the improvement of Th17 cells in patients.