Objective：To investigate the level of serum soluble growth stimulating gene 2 protein（sST2）and its correlation with the severity of coronary artery lesion in patients with acute coronary syndrome（ACS） undergoing percutaneous transtuminal coronary intervention（PCI） therapy. Methods：From July 1，2018 to December 31，2018，173 patients with ACS were selected from the Department of Cardiology，the First Affiliated Hospital of Nanjing Medical University. According to the diagnostic criteria in the critical care medicine emergency rapid diagnosis and treatment guide for ACS，they were divided into the unstable angina（UA） group，the acute ST segment elevation myocardial infarction（STEMI） group and the acute non-STEMI （NSTEMI） group. A total of 85 coronary angiography negative patients were enrolled as the control group in the same period. The results of TG，TC，LDL-C，LP（a），sST2，Killip classification were collected，and the correlations between sST2 and Gensini score，proBNP and Gensini score were analyzed. Results：Compared with the control group，sST2 level in the UA group has no significant difference，but they were increased significantly in the STEMI group and the NSTEMI group. Moreover，sST2 level in the STEMI group was higher than that in the NSTEMI group. Compared with the control group，Gensini score in the patients with ACS was significantly higher，which in the NSTEMI subgroup was higher than that in the STEMI group and the UA group. Serum sST2 level was correlated with Gensini score significantly（r=0.586，P < 0.001）. The proBNP level was correlated with Gensini score significantly（r=0.680，P < 0.001）. Conclusion：Serum sST2 level was positively correlated with the number of coronary lesions and the complexity of coronary lesions.