Abstract: Development of quantum-dot-array diffraction grating (QDADG)with single order diffraction properties is important for laser fusion research. The diffraction principle and fabrication method are introduced in this article. Diffraction properties of quantum-dot-array diffraction grating are studied when visible light radiates grating with different wavelength and incidence angle. It shows that QDADG can get rid of the influence of high order diffraction, which will solve the key problem (i.e. distortion from high order diffraction) of the present diffraction grating spectroscopy. QDADG for visible light is a potential alternative for X-ray, extreme ultraviolet and microwave diagnoses．