This paper analyses the positive criteria and diagnostic value of different indices of treadmill exercise test (TET). TET is a way of diagnosing coronary heart diseases（CHD） and estimating CHD patients' exercise tolerance. The principle of TET is that exercise can increase the load of heart, which leads to increased demand for oxygen of myocardium, and when the load meets the trigger point, which means overloading the ability of supplying blood of coronary artery, myocardial ischemia occurs, which can be revealed by electrocardiogram (ECG). The indices of TET mainly focus on the change of ST segment, especially on the depression of ST segment. In recent years, the other physiological changes caused by exercise have been studied to learn the relationship between these changes and CHD, such as the changes of QRS, blood pressure and heart rate recovery loop. TET has become an important approach of diagnosing CHD and estimating prognosis and therapeutic effect.