To develop the supplementary heart valve which could reduce the complications of prosthetic heart valve, in vitro experiments were performed to analyze the movement of the supplement valves from the view point of the flow dynamics and leaflet dynamics. The autologous pericardium was attached to deficient portion of the porcine valve which was dissected completely and partially. The pericardium was treated by buffered glutaraldehyde solution in the preshaped mould to preserve the shape of the leaflet. The function of the valves were evaluated in the mock circulatory system and three sets of experiment were performed. The instantaneous motion of the leaflet was pictured by the 35mm camera and the pressure drop through the valve and cardiac output were measured. The supplementary valve which was replaced completely performed better thatn the valve replaced partially. In vitro experiments showed that the supplementary valve which was replaced completely performed better than the valve replaced partially. In vitro experiments showed that the supplementary valve could undertake the prosthetic heart valve in clinic.