Abstract: Pulse Pressure and the change of pulse contour characteristics are of significant importance in the evaluation of physiological factors of man's cardiovascular system.In order to study the relationship between pulse contour characteristics and physiological factors,a new method for the extract of pulse contour characteristic value K is presented in this paper,which is based on the change of sphygmogram area and defined by K=(P_m-P_d)/(P_s-P_d),of which.P_m is the average pressure shown in the sphygmogram.The results of theoretical analysis and,experiments with the animals and clinical practice,K would reflect the total peripheral resistance,the hardness of the blood vessels and blood viscosity.The peripheral resistance and vessel elasticity of healthy young people are peoper,the K value of a healthy old man is about 0.35~0.4.One's peripheral resistance woud increases and his vessel elasticity would decrease with ageing.The aged people's K value would increase to 0.4~0.45.In a case of seriouse hypertension,the peripheral resistance and hardness of blood vessels are as high as the K value will be above 0.45.The results of the study shows that the pulse contour characteristic value K is a very important physiological index in the diagnosis of cardiovascular disease.