In this study, the distribution information of lemon planting and the surface observation data during 1971–2017 from meteorological stations in Sichuan Province are adopted to reasonably plan the layout of lemon planting in Sichuan Province. Considering the elements of climate, soil and terrain affecting the planting distribution of lemon, 16 ecological factors are selected for the analysis and regionalization of the ecological suitability of lemon planting in Sichuan Province. Specifically, the maximum entropy model is used to establish the model for the relationship between the planting distribution of lemon and one of its potential influencing factors related to the climate. On this basis, dominant climatic factors affecting the planting distribution of lemon are investigated, and the distribution for corresponding suitability grades of these climatic factors are also revealed. The receiver operating characteristic curve is used to verify the simulation accuracy. The Jackknife method and correlation analysis are used to screen dominant climatic factors and analyze their relationship with the existence probability. Based on the ArcGIS platform, the spatial distributions for the regionalization indexes of soil and terrain are analyzed for the soil and terrain suitability regionalization of lemon planting in Sichuan Province. Furthermore, by using the ecological suitability analysis method and considering the weights of various indexes, the ecological suitability regionalization of lemon planting in Sichuan Province is obtained. The results show that the highly suitable regions for lemon planting with an area of 29,000 km² are mainly concentrated in Guang’an City, Nanchong City, Suining City, Ziyang City, Neijiang City and Zigong City, and some regions scattered in the Sichuan Basin as well. In addition, there are also some highly suitable planting spots for lemon in Panzhihua City. The moderately suitable region covers an area of 39,000 km², and most of which are distributed in the mountainous areas in eastern part of the basin, such as the Guang’an City, Dazhou City, Suining City and Zigong City. The slightly suitable region with an area of 67,000 km² is mainly concentrated in the central Sichuan Province, surrounding the highly and moderately suitable regions. The unsuitable region covers an area of 53,000 km², which is mainly concentrated in plateau and mountainous regions of the western and northern Sichuan Province.