The authors proposed a method which combined the differential threshold segment with median filter to eliminate abrupt artifact motion interference in the use of pulse oximeter, and further more, by adding the window moving average filter, this method could reduce the periodic artifact motion interrupt in some way. In the experiment, the authors intently simulated the common finger motion to get the artifact motion “corrupted” signal with our self-made reflectance oximeter system. The comparison of the original PPG signal and processed PPG signal shows that the method we proposed performed well in an effort to reduce the common artifact motion interrupt. Finally, in order to figure out what effort this method can make for the accuracy of oxygen saturation measurement, the ration of AC and DC component in the red and infrared signal directly associated with the pulse oxygen saturation was calculated. The result indicates that this method can reduce the error caused by the artifact motion and stabilize the rate of false reading of pulse oximeter under the finger motion state. More importantly, this method needs only a small calculation cost, so it could be applied in the real-time PPG signal processing without the need of powerful hardware.