Objective To investigate the effect of intralipid postconditioning on myocardial enzyme in patients receiving extracorporeal circulation of cardiac valve replacement. Methods Forty patients undergoing cardiac valve replacement were randomly divided into two groups. Patients in the experimental group were given intralipid (200 mL) immediately after aorta opening from the extracorporeal circulation machine, and those in the control group were given 200 mL normal saline in the same manner. The radial artery blood samples were collected at the beginning of the operation, 0.5 h, 1 h, 2 h, 4 h, and 24 h after aorta opening. The serum lactate dehydrogenase (LDH), creatine kinase (CK), creatine kinase isoenzyme (CK-MB), and cardiac troponin I (cTnI) were observed and the blood gas analysis was performed. The hemodynamic parameters, time of cardiopulmonary bypass, time of aorta block, time of operation, recovery of heartbeat, the dosage of dopamine, assisted ventilation time, ICU detention time, 24 h urine amount, and 24 hour drainage amount after operation were all recorded in the two groups. Results There were no significant differences in hemodynamic parameters, dosage of dopamine used, spontaneous recovery of heartbeat, 24 h urine amount, or 24 hour drainage amount between the two groups (P>0.05). The postoperative levels of serum LDH, CK, CK-MB, and cTnI were significantly higher than those before operation in both groups (P<0.05).Compared with the control group, the LDH level in the experimental group was significantly deceased 24 h after aorta opening (P<0.05); cTnI and CK levels were significantly decreased 4 and 24 h after aorta opening (P<0.05); and CK-MB level were significantly decreased at 2, 4, and 24 h after aorta opening (P<0.05). Conclusion Intralipid postconditioning by cardiopulmonary bypass can reduce the release of myocardial enzymes in patients receiving heart valve replacement surgery, thus alleviate myocardial ischemia-reperfusion injury.