Objectives: To study the correlation between the resistance and the pulse wave,and the application of resistance in clinic. Methods: It puts forward the principle and arithmetic of resistance,the algorithm is based on the pulse wave theory and the model of Windkessel. The correlations of resistance and blood pressure are analyzed by testing 125 cases of hypertension patients and 125 cases of normal persons in clinic. Results: The algorithm proves effective and reliable through analyses of many cases and doing lots of clinical tests,which has been developed software under LabVIEW7.0 and applied in the hospital. Conclusions: It can give the information of the measurer's arterial stiffness and provide reference to doctor to determine the measurer's cardiovascular disease.