Objective　To study the factors effecting the formation of the ventricular aneurysm post myocardial infarction (MI) and evaluate the diagnostic methods.Methods　23 MI patients with ventricular aneurysm confirmed by left ventricular angiography were observed for electrocardiogram (ECG), echocardiogram (ECHO), coronary disease and collateral vessels formation. Results　All patients had LAD disease, 65.2% patients had three coronary disease, and those with class Ⅲ collateral vessels circulation only 17.4%. Compared to ECHO by which only 4 patients were found aneurysm, the positive rate by ECG was 82.6%. Conclusion　Patients with multiple coronary disease and without enough collateral vessels are expected to form ventricular aneurysm. ECG is more sensitive than ECHO for diagnosis of ventricular aneurysm post MI