Small Tertiary granite bodies are distributed extensively in the Himalayas area. According to their geological features and lithologie types two belts can be distinguished: (1) High Himalayan tourmaline-muscovite granite belt, i:e. south belt, and (2) South Xizang Lower Ridge dimicaceous gneissic granite belt, i.e. north belt. The former can be further subdivided into two parts - the stocks and veins. The composition and structure of the feldspars obtained from ten granite bodies were determined by various methods, e.g. optical, X-ray and infra-red absorption and so on.Basing upon these determinations the following conclusions may be drawn: 1. The K-feldspars in the bodies are essentially intermediate microcline or "tric-linic orthoclase", but not simply orthoclases; 2. The ordering of the plagioclase is always higher than that of the K-feldspars in the same body; 3. Owing to the presence of volatile component in large amount the ordering and triclinicity of K-feldspars in the stocks of the south belt are more significant than that in the stocks of the north belt; 4. As veins cool down more rapid by cooling than stocks, the ordering and triclinicity of K-feldspars in the stocks are also more significant than that of K-feldspars in the veins from the same belt; 5. The composition of plagioclases in the same granite body varies in a more narrow range with a normal frequency curves. In short, it is suggested that the structure of feldspars in granites does not only depend on the geological age of the formation of the granite body, but also on the thermal history and the concentration of the volatiles.