Oxygen is the basis of life activities,and hypoxia can cause many diseases.The system uses Samsung's S3C2440 ARM9 embedded microprocessor cores in order to achieve the oxygen saturation which is an important physiological parameters in real time and accurately monitor,make the system has good portability, stability and functional diversity .The system finished embedding Linux operating system 2.6.30.4 on S3C2440 transplantation, write, transplantation, and yaffs2 based root file system driver system. S3C2440 to communicate with integratedanalog front end AFE4400 via SPI bus, which realized the blood oxygen saturation data processing, analysis and display. Experiments show that the system is stable and efficient and has good stability.This system has built a very important significance embedded ARM_Linux medical monitoring system.