Objective A blood assist index (BAI), defined as ratio of the output power of LVAD (left ventricular assist device) to the total input power of circulatory system, was proposed in this paper to regulate the energy distribution between LVAD and natural heart. Methods A control strategy based on model free adaptive control (MFAC) algorithm was designed by using BAI as the control variable. The algorithm could track the desired BAI by regulating the pump speed to maintain the measured BAI. A mathematic model of cardiovascular system was used to verify the feasibility of the controller in presence of heart failure, slight physical active and recovery of cardiac function. Results The simulating results demonstrated that the proposed controller could automatically regulate the pump to respond to the reduced peripheral resistance (5 500 r/min vs. 6 000 r/min). When Emax increased from 80 to 240 Pa/mL to simulate the heart recovery, the blood flow rate could increase accordingly from 5 to 8 L/min.Conclusions The proposed control strategy can provide an adjustable and accurate energy distribution between LVAD and native heart by regulating the pump speed, which would be of benefit to promoting left ventricle reverse remodeling.