To explore the immune function of sub-healthy people, and analyze the therapeutic effects of Xiaoyao Pill on immune function.Methods:A total of 78 cases of sub-healthy patients with liver depression and spleen deficiency pattern who were treated and diagnosed in our hospital from May 2015 to February 2016 were randomly included into the treatment group, and treated with oral administration of Chinese patent medicine Xiaoyao Pill.The fatigue assessment instrument (FAI) and self-rating anxiety scale (SAS) of patients before and after treatment were measured.And the changes of serum levels of immunoglobulin G (IgG), immunoglobulin A (IgA), T Helper 17 (Th17) Cells before and after treatment were detected.They were compared with healthy adult volunteers came to our hospital for physical examination.Results:According to the symptoms, sub-health state was divided into 5 types of depression and gloomy, distention pain in chest, dizzy, anorexia and abnormal menstruation.Among them, abnormal menstruation type accounted for the largest.In the treatment group, the SAS, FAI scores and Th17 were significantly decreased (P<0.05).Serum levels of IgG and IgA were significantly increased (P<0.05).Conclusion:Xiaoyao Pill can greatly improve the immunity of sub-health population, and can inhibit abnormal activation of Th17 cell by reducing the level of Th17 in peripheral blood, inhibit hyperfunction of T lymphocyte, as well as repair damaged immune system.