Testing the ordinary gemological features and using methods of microscope optical observation, X-ray powder diffraction and electron microprobe analysis, the authors studied the structure, composition and color mechanism of Dushan jade from Nanyang, Henan Province. The results indicate that the primary mineral components of Dushan jade are zoisite, edenite, mica and plagioclase which has experienced alteration in various degrees. The celeste color is related to the mica which contains chromium, the green color of the greenish pink jade has something to do with epidote, the green part of the whitish green jade is actually the mineral diopside which contains masses of iron and chromium. The purple color is attributed to Ti- and Cr-bearing biotite and sericite in the Dushan purple jade. Zoisite in the pink jade that causes the pink color and black color is in connection with edenite. The color transitions of black Dushan jade is related to the alteration extent of plagioclase which also transforms to various minerals.