Objective To understand the coronary characteristic of acute coronary syndrome patients with ischemic J wave. Methods Comparison was made between 60 acute coronary syndrome patients with ischemic J wave and 60 acute coronary syndrome patients without ischemic J wave. All patients were examined by Holter monitoring electrocardiogram and coronary arteriongraphy. To distinguish the stenosis degree was defined in three degree based on Genisini score of 0, 1-80, and 81-160. Plaque types were divided into Ⅰ,Ⅱ, Ⅲ by Ambrose classification,the coronary and plaque characteristics of acute coronary patients were observed with ischemic J wave. Results There were no significant difference of stenosis degree between the two groups ( U = 3. 0686, P = 0. 0022), whereas there were significant difference of plaque types (x2 =16. 0890, P = 0. 0003) and coronary vessel numbers(x2 =12. 1045, P = 0. 0024). The degree of stenosis, the plaque types, and number of stent in coronary vessel were positively correlated with ischemic J wave(r =0. 44,0. 34,0. 31 ;P <0. 05). Conclusions The acute coronary syndrome with ischemic J wave patients is often not only accompanied with serious coronary stenosis and high incidence rate of multivessel disease,but also high probability of unstabilized plaque. Ischemic J wave can be a predictor of super-acute ischemic of myocardium.