Objective A portable blood-oxygen monitor system is design to detect the incidental hypoxia and cardiovascular diseases apnea, which can be adorned on the patients with sleep apnea. Methods With the FPGA developing system DE2 produced by Jingyou Technology Company of Taiwan as the hardware platform, the system is set up using the development tool SOPC Builder, and the systems software is developed in the integrated development environment of NiosII IDE. The SOPC technology of ALTERA Company is adopted, and with the DE2 development board at the core, the system can judge whether there exist sleep apnea by detecting and recording the respiration, oxyhemoglobin saturation, pulse and the frequency of snore. Results The system can determine whether the body is normal or not during sleep, and give an alarm and stimulation in a critical condition. Conclusions The system has the features of simplicity of operator, portability, low power consumption and so on. All the data can be synchronously displayed and saved, it is convenient to tail after and process later.