In order to improve imaging performance of CCD camera, the CCD noise is categorized and analyzed, and high SNR video signal processing circuit is designed. The principle of Correlated Double Sample (CDS) circuit, which is aimed at processing reset noise and 1/f noise, is discussed. Video signal processing circuit is designed with specific video processing chip VSP2270 and FPGA as the core. At last, the experiments of image acquisition and SNR test are introduced together with CCD driving circuit. The results show that the video signal processing circuit effectively inhibits reset noise and 1/f noise, but the circuit noise itself is small. The system SNR reaches up 58.4 dB when data rate is 20 MHz, which meets the requirements of star map imaging.