A fingerprint detecting system comprises a fingerprint module, for receiving a fingerprint driving signal and performing a frequency modulation on the fingerprint driving signal, to correspondingly outputting a fingerprint signal with a first frequency based on the fingerprint driving signal, and a signal processing circuit, coupled to the fingerprint module, for receiving the fingerprint signal with the first frequency, performing a frequency demodulation to shift the first frequency of the fingerprint signal to a second frequency, and filtering the fingerprint signal with the second frequency based on the first frequency, whereby the filtered fingerprint signal is used for a fingerprint data analysis.