Abstract: In view of the difference from LED source and traditional sources,a new LED lighting simulation system based on DirectX is developed.The paper has investigated the advantages of developing the system by DirctX9 SDK,and combine the basic theoietical knowledge of computer graphics and optics to research the principles and main components of LED simulation system.It presents a LED model solution and a human- computer interactive interface design,and analyzes the simulating results of this system.