Abstract: To investigate the efficacy of Liupao tea on regulating phlegm-dampness constitution in sub-health state and the mechanism, a randomized, controlled clinical trial of 90-day was taken using Liupao fresh and aged tea with the intervention dose of 10 g soaked in boiling water of 200 ml for 2 min, twice a day as the intervention means. Traditional Chinese medicine diagnostic indexes and blood biochemical indexes related to phlegm-dampness were recorded before and after intervention, and the change of intestinal flora was analyzed. The results indicated that the phlegm-dampness quality translation score showed a decreasing trend in the middle and end of the intervention among the fresh tea intervention group and aged tea intervention group. The ANOVA results showed the phlegm-dampness quality translation score of fresh tea intervention group had significant differences at three time points of 25, 45 and 90 d after intervention (P<0.05). The intervention of Liupao tea could improve the phlegm-dampness constitution slowly and the effect of fresh tea was slightly faster. Biochemical results showed that Liupao tea had the effect of reducing bilirubin (total bilirubin and direct bilirubin). The effect of aged tea was obvious and the difference was statistically significant (P<0.05). Intestinal flora results showed that the level of Bacterioidetes decreased to 0.49±0.17 in fresh tea intervention group and 0.48±0.35 in aged tea intervention group, while the level of Firmicutes increased to 0.42±0.23 in fresh tea intervention group and 0.45±0.08 in aged tea intervention group after intervention. The relative abundance of Bilophila increased to 0.0024±0.0013 in fresh tea intervention group and 0.0022±0.0034 in aged tea intervention group. Liupao tea changed the relative proportion of Firmicutes and Bacteroidetes in the intestinal flora, promoted the increase of Bilophila, thus Liupao tea may improve the metabolism of blood bilirubin by regulating the bile acid pathway. The relative abundance of Sutterella, Izimaplasmatales and Ruminococcus, which are related to metabolic diseases and energy metabolism, were changed during the experiment. Therefore, Liupao tea may improve the metabolic state of sub-health people by regulating intestinal microbiota.