Backgrounds: The aim of this study was to explore the possible correlations of serum interleukins and soluble ST2 (sST2) protein with clinical features and inflammatory cytokines in rheumatoid arthritis (RA) patients, as well as to assess ability of TCM (Traditional Chinese Medicine) syndromes to differentiate RA patients and evaluate prognosis. Material/Methods: Thirty RA patients and 25 healthy individuals were enrolled. Syndrome activity was evaluated, and lab tests were performed. Serum levels of IL-10, IL-17, IL-33, and sST2 were assessed by ELISA. Results: Serum levels of sST2, IL-33, and pro-inflammation cytokine IL-17 were all up-regulated, while the immunosuppressive cytokine IL-10 was decreased in RA patients. Serum IL-33 level was positively associated with ESR, CRP, and RF, as well as with HAQ score, VAS score, and DAS28 scores (P<0.05). Serum sST2 level was correlated with the morning stiffness time and ESR, as well as scores of HAQ and DAS28 (P<0.05). In addition, IL-33 level was positively corelated with IL-17 (r=0.83, P<0.01) and the relative ratio of IL-10/IL-17 (r=0.904, P<0.01), and was negatively related with IL-10 (r=-0.632, P<0.01). TCM syndrome differentiation was conducted for RA patients, including the hot syndromes and cold syndromes groups. Hot syndromes RA patients had significantly more severe inflammation compared with cold syndromes patients. Conclusions: IL-33 is a possible index for monitoring disease activity and inflammation condition in RA. IL-33 contributes to RA pathogenesis through unbalancing IL-10 and IL-17. In terms of TCM, hot syndromes RA presented more serious inflammation and more active disease activity, indicating a poorer prognosis.