Aimingatthedisadvantageoflowaccuracyofbloodoxygensaturationmeasurementunderlowperfusionbythe peak-valley method, an improved method based on convolution modeling is adopted to measure blood oxygen saturation. The method is based on the periodicity and sparsity of the pulse wave. By analyzing the characteristics of the photoplethysmographicpulsesignalanditsconvolutionsignal, theconvolutionsignalisusedinsteadofthepulsesignal to measure the blood oxygen saturation. The experimental results show that the proposed improved method is similar to the peak-valley method in the normal perfusion index, and the average deviation and accuracy of the peak-valley method are 5.304and3.296undertheconditionoflowperfusionindexto0.2%, respectively.Theaveragedeviationandaccuracyofthe method are 1.224 and 1.443, respectively. The improved method has higher measurement accuracy and better stability, whichprovidesaneffectivewaytomeasurehumanbloodoxygensaturation.