：High gain photon detectors such as avalanche photo diode(APD)are widely used for high-sensitivity photon detection.However,the high voltage applied to these detectors often makes serious noise.In order to perform high-sensitive photon detection,an innovative denoising design for charge-sensitive preamplifier is proposed,which can reduce the power-supply noise by differential amplification.Firstly,the junction capacitance of APD is tested under various bias voltages.Then capacitance matching is made with an adjustable capacitor and circuit simulation is performed with Multisim software.Finally the fabricated circuit is tested.It is shown that the charge-sensitive pre-amplifier with differential input can significantly reduce the power-supply noise(both low frequency and high frequency)and realize high sensitivity.