A datum warning method and a datum rebuilding method are applied to a bio-sensor module equipped in a wearable electronic device. The wearable electronic device includes a warning interface and a bio-sensor module coupled with the warning interface. The bio-sensor module includes a sensor and a processor electrically connected with the sensor. The sensor is adapted to continuously receive a plurality of physical signal. The processor is adapted to identify if one specific physical signal meets a predefined condition, and output a warning signal to show a reminder via the warning interface when the specific physical signal is identified. Further, the processor is adapted to display each of the physical signals via the warning interface, and replace at least one of the physical signals and then store the replaced physical signal with non-replaced physical signals for rebuilding a statistic curve.