Based on SOPC (system on programmable chip)，the hardware and software designs of the image processing system are introduced. The controller IP cores of the CMOS image sensor and VGA display are designed to acquire and display the images respectively. The algorithm of the image edge detection based on the Sobel arithmetic operators is used by the Nios II soft core. Using this system a good real-time performance can be obtained，and the software and hardware designs of image processing system are greatly simplified.