1. Continuous blood oxygen monitoring: Pair the Watch Pro with the app. In the app, go to the health check feature and select Continuous Blood Oxygen Monitoring. Set the switch to on. Put on the Watch Pro and it will start to automatically measure your blood oxygen once every 30 min. 2. Manually measure your heart rate: Put on the Watch Pro, and remain still. Press the button to open the function list, and select Blood Oxygen Saturation. Tap to enter, and the Watch Pro will start to measure your current blood oxygen.