Abstract:A water and thermal product index was in attempt to be established according to the relations among annual average temperature, annual precipitation, potential evapotranspiration and soil water balance. The plant community groups were constrainted to form a circular life-climate diagram using three climatic indices, annual average temperature, annual soil water surplus and deficit, and water and thermal product index. Based on the records of 689 meteorological stations of China, the annual average temperature, soil water surplus and deficit, water and thermal product index of 8 vegetation zones and 26 subzones were calculated. The vegetation types included cold-temperate (boreal) coniferous forest, cool-temperate mixed coniferous-broadleaved forest, warm-temperate deciduous broadleaved rain forest, subtropical evergreen broadleaved forest, tropical forest and monsoon rain forest, temperate steppe, temperate desert and Tibetan high-cold plateau alpine vegetation. Additionally, distributional and scatter graphs of every climatic index were drawn. All of these highlighted well the relationship and pattern between vegetation and climate in China. The isopleth of annual average temperature relatively reflected the thermal gradient in China. The differences in latitude and longitude were significant. The isopleth of soil water surplus and deficit was scattered. The isopleth of water and thermal product index not only showed better relation to thermal and water gradients but also to vegetation types. The study was an attempt of under standing the vegetation-cli- mate interaction at a large scale which merits more understanding of its mechanism, such as the interaction and feedback between vegetation and climate, plant population, and soil characteristics, etc. to further improve this method.