Peak wavelength,bandwith,domain wavelength,and centroid wavelength are factors affecting on light color of LED.Peak wavelength and bandwith stand for the physical property of light of LED,domain wavelength corresponds to feel of eyes,centroid wavelength is geometric symmetry wavelength of LED.They were measured using concave dispersion system and CCD.Their accuracies are 1 nm.Domain wavelength was estimated by centroid wavelength,its error is less than 3 nm.