There are many mountains and vast plateaus in the western region in China.Owing to the influence of vertical zonality,It is difficult to divide the climatic belts.But the vertical climate is established based on the base vertical climatic belts that have the characters of latitudinal zonality.Therefore,the divided western sub-tropical thermal belts are latitudinal zones.Thereafter,YunnanGuizhou Plateau and Jinsha River Velley should be in the middle sub-tropical zone.The latitudinal zonality is destroyed by the Tibetan Platearu.Therefore,there is a boundary of western sub-tropical zone which is located on the eastern side of the Tibetan Plateau.It is a boundary on the north,the middle and the south of the sub-tropical which runs into the Tibetan Plaleau.But there is not a transitional zone between the sub-tropical belt and the Tibetan Plateau.The method of dividing the western subtropical is advanced in this paper.