A wearable blood pressure detecting device is provided. The wearable blood pressure detecting device includes a pulse detecting module, a processing unit, a memory unit, a model selecting unit, and a blood pressure calculating unit. The pulse detecting module is configured to generate a pulse waveform. The processing unit is configured to capture the pulse waveform to generate at least one pulse characteristic value. The memory unit is configured to store at least two blood pressure models corresponding to different pulse characteristic value ranges. The model selecting unit is configured to select a corresponding blood pressure model according to the at least one pulse characteristic value. The blood pressure calculating unit is configured to calculate a blood pressure value by the selected blood pressure model.