The chrysotile asbestos deposits in ultramafic rocks of Northwest China ean be divided into three types, i.e.,Mangya type, Xiaobabao type and transition type. A number of chrysotile asbestos samples from different mineral deposits were studied by means of scanning electron microscopy and high-resolution transmission electron microscopy. As a result, the authors have obtained high-quality mierographsandlattice images for these samples. A contrastive study of the characteristics of electron micromorphology and lattice images of chrysotile asbestos fibers from different types of ore deposits shows that the asbestos fibers of Mangya type and Xiaobabao type differ rather obviously from each other in such aspects as cleanliness of fiber face, diameter of inner tube or [thickness of tube wall, filling state of inner tube and associated minerals among fibers, flexibility, properties of lattice images, and structural defects. The asbestos fibers from Northwest China might be divided into soft type and hard and stiff type. The fibers of Mangya are different from those of Xiaobabao in physical properties and uses. The tectonic Setting, fiber-forming temperatare, stability of minerogenic geochemical process and media are basic factors affecting the growth of fibers and the crystallochemical characteristics of chrysotile asbestos, and this accounts for the differences mentioned above.