Abstract: The maximum entropy model (MaxEnt) is an effective tool for agricultural climate suitability regionalization due to its objective, quantitative characteristics and good performance. Many representative planting sites in the study area is required by this method as statistical samples. However, the current scale of pecan planting in Yunnan Province is relatively small, and the spatial distribution of planting sites is too scarce to meet the model construction requirements. Therefore, it is difficult to obtain reliable results by directly applying this model to the climatic suitability zoning of pecan.Based on MaxEnt model and Geographic Information System (GIS), an improved method of agricultural climate suitability regionalization is proposed. Regionalization of climate suitability for pecan crop in Yunnan Province of China is carried out based on local climate data combined with data from 274 pecan planting sites in the contiguous United States. Results show that the dominant factors affecting the climate suitability of pecan crop are as follows: The average temperature in July, annual average temperature, extreme minimum temperature of 30 years, annual amount of precipitation, amount of precipitation from March to May, annual accumulated sunshine hours and accumulated sunshine hours from April to May. The MaxEnt Model based on climate data from 274 pecan planting sites in the contiguous United States has high accuracy in corresponding areas. In order to apply this model in Yunnan properly, a reliability factor is introduced to improve the climate suitability index by means of modeling areas as well as the deviations of climate factors of training samples. Then based on this improved climate suitability index, the climate suitability of pecan plantation in Yunnan Province is divided into 4 grades: Optimum, suitable, sub-suitable and unsuitable, among which the areas for the optimum and suitable areas are distributed in subtropics areas and tropical marginal areas, with abundant heat resources, relatively sufficient sunshine hours and favorable chilling condition in winter. Due to the complex terrain and climatic conditions in Yunnan Province, regionalization results are substantially fragmented.