AIM: To explore the effects of Jianpi Huatan formula on regulating T cells and helper T cells 17 (Th17) cells in patients with polycystic ovary syndrome (PCOS) due to spleen deficiency and phlegm dampness syndrome, and conduct a model evaluation. METHODS: Ninety-two patients with spleen deficiency phlegm dampness syndrome (PCOS) admitted to our hospital from January 2023 to October 2024 were selected as the research subjects. Propensity score matching (PSM) method was used to match them in a 1:1 ratio, with 46 patients in each group. The control group received conventional treatment, while the observation group received treatment with Jianpi Huatan formula on the basis of the control group. Compared and analyze the differences in clinical data and laboratory indicators between two groups; Compared the changes of sex hormone, glucose metabolism and TCM syndrome score before and after treatment in the two groups, and focused on the changes of regulatory T cells (Treg) and Th17 cells in the two groups before and after treatment; And used the Generalized Estimation Equation (GEE) model to analyze its improvement. Multiple linear regression analysis was used to examine its correlation with the score of traditional Chinese medicine syndrome. A time effect model of Jianpi Huatan formula for treating PCOS with spleen deficiency and phlegm dampness syndrome was established using a nonlinear mixed effects model. The fitting effect of the final model was evaluated through the goodness of fit. Bootstrap was used to test and evaluate the stability of model parameters. Visual prediction testing was used to evaluate the predictive performance of the model. Typical time effect curves of traditional Chinese medicine symptom scores was simulated based on the final model for each baseline. RESULTS: After treatment, the total effective rate of the observation group was significantly higher than that of the control group (χ2=4.842, P=0.028); Compared with before treatment, after 1months and 3 months of treatment, TC, TG, LDL-C, T, LH, FSH, AMH, FPG, FINS, HOMA-IR, the score of traditional Chinese medicine syndrome were significantly reduced, while E2 and HDL-C were significantly increased, and the improvement in the observation group was significantly greater than that in the control group (P<0.05);The results of repeated measures ANOVA showed significant differencesin the time effects, inter group effects, and interaction effects of Treg, Th17, and Treg/Th17 between the two groups of patients (P<0.05) . The GEE analysis results showed that the improvement of Treg, Th17, and Treg/Th17 in the observation group were better than that in the control group (P<0.05);The results of multiple linear regression analysis showed that the levels of TC,TG, LDL-C,T, LH, FSH, AMH, FPG, FINS, HOMA-IR, Th17 were significantly positively correlated with TCM syndrome score, while the levels of E2, HDL-C, Treg, and Treg/Th17 were significantly negatively correlated with TCM syndrome score (P<0.05); The decrease in traditional Chinese medicine symptom score compared to baseline gradually increases over time, eventually reaching the pharmacological platform, which was consistent with the classic Emax model. After gradually screening covariates, it was found that the baseline value of traditional Chinese medicine symptom score had a significant impact on the efficacy parameter Emax. The final model was Emax, i=15.42+1.21×(Baselinei-24.41). The goodness of fit results showed that the final model had a good fitting effect on the measured data. The model parameters obtained from Bootstrap testing were very consistent with the original model, indicated that the model parameter estimation was robust. The visual prediction test results showed that the model had good predictive performance. The typical efficacy time curve showed that the higher the baseline value of TCM symptom score, the greater the decrease in score. At 3 months of treatment, the TCM symptom score at each baseline basically decreased to below 10 points. CONCLUSION: The formula for strengthening the spleen and resolving phlegm can effectively improve the levels of Treg and Th17 in PCOS patients with spleen deficiency and phlegm dampness syndrome, and has good therapeutic effects, which is worthy of clinical application.