Abstract: At present, then are still some controversial considerations on the closing mechanism of natural heart valves. In this area, a lot of phenomena still remain mysterious, particularly for the mechanism of earlier partial closure of the valve while the blood ejection is still in its acceleration phase. It is the purpose of this study to focus on the problem of earlier closure mechanism of heart valves hy using both theoretical analysis and experimental verifications. A certain two-dimensional mathematical model of closure with all contributing factors and the whole operating process being considered is in vestigated with a new analytical method. Several new conclusions were found. The main points are as follows:1. During the opening phase. the main factor of motion of the valve is the accelerating flow, and the decelerating flow plays a main role during most the of time of the deceleration phase. But during the quasi-steady phase of blood ejection, it is the vortex in the sinus that controls the valve closure.2. For the earlier partial closure of the valve during the acceleration phase, the vortex is a decisive factor, hut its function is limited. It is found in the same time that without the vortex, the valve can still close in a similar manner, but there will be no earlier closure during the acceleration phase which characterizes the situation of being with vortex.3. It is ascertained that the existence of the sinus is essential to the effective closure of the valve.In addition, the effects of the valve length, frequency and peak flow rate of the motion of the valve are studied in this paper. Such studies are useful for the design of artificial heart valves.