To observe the influence of improving the fatigue and the cellular immune function by intervention with Xiaoyao pills for sub-health population, and to analyze the mechanism. Methods:Sub-health population who had physical examination in Physical Examination Department in Shijiazhuang First Hospital from January 1st 2016 to December 31st, 2016 were selected. A total of 40 patients were included into the observation group by random numbers method, meanwhile 20 cases of healthy people were selected randomly as the control group. The observation group was orally given Xiaoyao pills, and the control group didn't have intervention treatment. Fatigue Self-Assessment Scale (FSAS) and Sub-health Measurement Scale (SHMS) of the two groups before and after the intervention were evaluated and recorded, and the serum immunoglobulin IgA, IgG, Th1/Th2 ratio in the patients were quantitatively detected. Results:1) Before treatment, the differences of FASA, SHMS, IgA, IgG, Th1/Th2 ratio in the two groups were statistically significant (P<0.05). After 4 weeks of treatment, FASA and SHMS increased in the observation group than before treatment, and there were no statistically differences compared with the control group (P>0.05);2) After 4 weeks of treatment, the serum IgA, IgG levels of patients in observation group increased significantly (P<0.05), and close to the healthy control group. The two groups were with no statistical differences (P>0.05). 3) The Th1/Th2 ratio of the observation group was lower than that of control group. After 4 weeks of clinical intervention group, Th1/Th2 ratio of the observation group increased, but was lower than healthy control group. It had significant improvement than before the treatment, and the difference was statistically significant (P<0.05). Conclusion:Oral administration of Xiaoyao pills can reduce the degree of fatigue in sub-health population, improve the human cellular immunity, as well as improve the sub-health status.