Rabbit hair has been expected to be a partial replacement of cashmere, due to its excellent performance and relatively cheaper price. However, the attempt has not been successful, since the morphological structure of the rabbit hair is quite different from other animal hairs. The literature regarding rabbit hair is fairly rich, but the morphology of rabbit hair is too complex to make a very certain conclusion. Hence, the morphological structure of rabbit hair was investigated again in this study, using optical microscopy and the scanning electron microscopy. The basic shape of the hair scale, the cortex distribution and the medulla of different fineness were studied. It was founded that no medulla existed when the diameter was less than 10um. When the fiber diameter was between 10um and 20um, there was normally one medulla layer. Two and three medulla layers occurred when fiber diameter was between 20um and 30um. When the diameter was more than 50um, multi-layers of medulla presented. Keywords: Rabbit Hair, Morphological Structure, Scale Layer, Cortex Layer, Medulla Layer.