To solve the problems of the circuit complexity and poor real-time performance existed in traditional pulse oximetry monitoring system,an efficient real-time method is proposed.Based on the photoplethysmograph (PPG),a digital hardware system is constructed with the light to frequency conversion technology.This system adopts zero phase digital filter and wavelet analysis technology to realize pulse oximetry preprocessing,and employs linear regression algorithm to complete the pulse oxygen saturation (SpO2)calculation.By using this method,the standard signals in the range of 70％~100% derived from Fluke Index 2 XL oxygen simulator have acquired error rate less than 2%.The results indicate that,this efficient method has the advantages of low complexity of circuit and high utilization rate of data,and can refresh the SpO2 value at the level of second.