Measurement of blood oxygen saturation to observe whether there is hypoxia is a very important clinical indication. There is no clear method to determine which finger to clip, and it can be done in the normal way plus the index, middle and ring fingers. For the little finger and thumb, it is less used because the little finger is smaller and easy to clip crookedly, which affects the measurement effect. If you clip the fingers, you also need to dynamically observe whether the clamping is correct or not. If the clamping is not done in the right way, it will also affect the correct result. At the same time of oxygen saturation measurement, it is also necessary to observe the general condition of the patient, whether there is chest tightness, chest pain or shortness of breath and other manifestations, and if necessary, it is also necessary to improve the common analysis of blood gas analysis examination.