The oxygen saturation of blood is an important vital sign. This paper proposes a new method of continuous noninvasive measurement of oxygen saturation based on blood video by extensively analyzing the physiological mechanism depending on arterial blood volumepulsewave and reviewing the principle and method of oxygen saturation measurement based on volumetric pulse wave. This method first uses mixed light to irradiate the arterial blood and captures blood stream video with mobile-phone cameras, then calculates the arterial blood oxygen content according to the blood flow volume and continuous changes in blood color. By comparing the measuring results with those from professional equipment, it shows the proposed method is with high accuracy, stable and reliable.