A wearable device is provided. The wearable device includes an optical sensor and a controller. The optical sensor is adapted to emit at least one optical signal, and receive at least one reflective signal corresponding to the at least one optical signal. The at least one reflective signal includes a physiological information. The controller is coupled to the optical sensor, and includes a signal filter. The signal filter is adapted to perform a signal processing operation to the at least one reflective signal according to at least one signal processing parameter. The controller adjusts the at least one signal processing parameter of the signal filter according to the physiological information. A method of operating the wearable device is also provided.