31 cases of sudden coronary death (within 1 hour, unexpected death) in 160 autoptic cases of coronary heart disease were studied (19.4%), including 24 male and 7 female; age 16-79, average 59.5. Most cases of sudden death had no obvious inductive causes. 18 patients died without cardiac symptoms, including those died before admission or during deep sleep. There was atherosclerotic stenosis (grade 4), of the coronary artery in 25 cases, of which 18 cases were with multiple branches involvement (grade 4) and 7 cases were with simple branch damage. Myocardial infarction was found in 24 cases, and myocardial ischemia in 7 cases. Old myocardial infarction was seen in 14 cases, and it was combined with acute myocardial infarction in 8 cases. Simple acute myocardial infarction was only seen in 2 cases. 8 cases showed ventricular aneurysm and 1 patient died of cardiac rupture. Conclusively, severe coronary stenosis and myocardial infarction are considered as one of the important bases of sudden coronary death.