Paired experimental design was adopted in this experiment for comparative observation on effect of electric acupuncture (EA) of Neiguan (P 6) at Chen Time (7 a.m. to 9 a.m.) versus Xu Time (7 p.m. to 9 p.m.) on left ventricular function in patients with coronary heart disease (CHD). The results show that EA performed at Chen Time could improve the left ventricular function of CHD patients as indicated by shortening of PEPI and decrease of PEPI/LVETI ratio; on the contrary, EA performed at Xu Time prolonged PEPI and raised PEPI/LVETI ratio in CHD patients, suggesting impairment of left ventricular function.