The present invention provides an image sensor circuit with a power noise filtering function and a control method thereof. The image sensor circuit includes: an image sensing unit, for sensing an image, to generate an image sensed signal; a power noise sensing unit, for sensing a power noise, to generate a power noise signal; a differential amplifier circuit, which is coupled to the image sensing unit and the power noise sensing unit, for receiving the image sensed signal and the power noise signal, to generate a differential filtered signal by a differential amplification operation between the image sensed signal and the power noise signal; and an analog-to-digital converter (ADC) circuit, which is coupled to the differential amplifier circuit, for receiving the differential filtered signal, to generate a digital image signal.