Cardiac resynchronization therapy(CRT)is an important therapy for patients with heart failure with a reduced ejection fraction and interventricular conduction delay. Large trials have established the role of CRT in reducing heart failure hospitalizations and improving symptoms and left ventricular (LV) function. However, the problem is how to maximize the response in CRT patients. The choice of patients, individual left ventricular lead placing, research progress in the application of new problems such as CRT transmission technology are summarized.