Aim To investigate the relationship between serum transforming growth factor β1 (TGF-β1), soluble suppression of tumorigenicity-2 (sST2) and the length and severity of thoracic aortic aneurysm (TAA), and to analyze the diagnostic value of serum TGF-β1 and sST2 in the diagnosis of TAA. Methods A total of 72 TAA patients (TAA group) admitted to West China Guang'an Affiliated Hospital of Sichuan University from July 2018 to December 2020 and 77 healthy volunteers (control group) were selected. Serum levels of TGF-β1, sST2, inflammatory factors and fibrosis indexes were detected. The lesion length and lesion degree of TAA were measured by echocardiography. Pearson or Spearman correlation coefficient was used to describe the correlation between TGF-β1, sST2 and lesion length, lesion degree, inflammatory factors, fibrosis indexes. Logistic regression was used to analyze the risk factors of TAA and the value of TGF-β1 and sST2 in the diagnosis of TAA was analyzed by receiver operating characteristic (ROC) curve. ResultsThe levels of serum TGF-β1 and sST2 were higher in TAA group than those in control group (t＝18.0,7.534, P＜0.05). Serum TGF-β1 and sST2 levels were positively correlated with the length of thoracic aortic lesion, the degree of thoracic aortic lesion, interleukin-1β(IL-1β), interleukin-6(IL-6), interleukin-33(IL-33), hyaluronic acid(HA), type Ⅲ procollagen(PCⅢ), type Ⅳ collagen, Ⅳ-C), and laminin(LN) (r/r_s＝0.751～0.921, P＜0.05). High levels of IL-33 (OR(95%CI)＝1.250(1.062～1.471)), PCⅢ(OR (95%CI)＝1.390(1.131～1.707)), Ⅳ-C(OR(95%CI)＝1.141(1.005～1.296)), TGF-β1(OR(95%CI)＝2.447 (1.370～4.372)) and sST2 (OR(95%CI)＝1.749 (1.327～2.306)) were risk factors for TAA (P＜0.05). The area under curve (AUC) of combined TGF-β1 and sST2 for diagnosis of TAA was 0.826, which was higher than that of TGF-β1 and sST2 alone (P＜0.05). Conclusion The increase of serum TGF-β1 and sST2 levels is associated with the occurrence of TAA, the length and degree of TAA lesion, and can be used as a potential indicator for the evaluation of TAA disease.