The article first compares the two existing design methods of FPGA, concentrating on the advantages of graphical programming, then taking the Sobel edge detection algorithm as an example, a digital image processing system is built on the Matlab/Simulink platform based on the System Generator design tool. The graphical modeling and online simulation of the algorithm are completed and the design result is compiled into Hardware Description Language (HDL). Finally, the function verification and test result analysis are carried out, and the results of visual processing of graphical modeling, RTL view, actual consumption of resources, and running speed are discussed.