In view of the problem caused by high-frame rate image sensor to analog-to-digital converter of video image, video image preprocessing circuits are designed. Through several important links, such as impedance matching, video buffer amplifier, video DC restoration, synchronous separation, synchronous clipping, low-pass filtering, DC adjustment and driver, these circuits eliminate all kinds of noise signals produced during gathering images, and adjust analog video image to the dynamic range required by analog-to-digital converter. Experimental results show that the images preprocessed in these circuits have advantages of short time delay, good quality, high SNR, better clarity and stability.