The present invention relates to a filtering device for dual band sensing circuit and a method thereof. The present invention is characterized in that a dual band sensing unit provided on a filtering device is used for receiving signals from a different frequency band subsystem and performing frequency division, then, one or more frequency band detecting units are used for detecting energy of signals at the high frequency band and the low frequency band and converting the energy into voltage, and users can adjust the gain of a tunable gain amplifier through an external part, perform a comparison operation by using a comparison unit, and control the switch time of a radio frequency switch unit with the help of generated signals, therefore, an adaptive notch filter effect is achieved, the notch filter with a high frequency or a low frequency is started by judging the current interference intensity, thus, in-band wastage is reduced.