The quality of Chinese herbal medicine is closely related to its producing region. In order to apply mathematical models to do a quantitative study on the suitability of Chinese herbal medicine, it is necessary to study on the ecological factors and the interpolation of climatic data, which influence the Chinese herbal medicine growth. The paper firstly studied the judgment standard of ecological index from the points of ecology and statistics, and how to calculate the optimum range values and the weight of each ecological factor. Secondly, meteorological element data is essential data in analyzing the suitable region of Chinese herbal medicine, and the spatial distribution of meteorological elements is closely related to terrain environment, so, in order to make the results close to true value by the greatest degree. The paper adopted multiple linear regression interpolation method which based on DEM. The paper distinguished the factor system of suitable region and interpolation on the point of datumization, and made a study on it about some key issues.