With phenotypic plasticity, plant individuals with the same genotype show different phenotypes in different environments. The characteristic lets species adapt to heterogeneous environments and have wider niches. Broad studies of phenotypic plasticity at the population and species levels are revealing the ecological significance of wild plants and also enrich the understanding of population distribution. Schisandra sphenanthera is a main species used for wild medicinal materials but is becoming scarce. Research and protection of the species is necessary. Leaves are the main organs of photosynthesis of S. sphenanthera, whose phenotypes vary with environmental changes. Analysis of phenotypic plasticity of leaves at the population level will reveal the plasticity of leaves, explore the effect of environmental factors on leaf phenotypes and provide the basis for the protection of S. sphenanthera. In this study, we analyzed the phenotypic plasticity of S. sphenanthera leaves on a large scale (9 provinces/cities, 26 counties, 27 populations) by using GIS technology. The 2 methods we used were phenotypic plasticity index and variation coefficient. We analyzed the effect of environmental factors on leaf phenotypic plasticity by using membership function and maximum entropy modeling. The environmental factors were of 3 types (edaphic, climate and topographic), including 13 factors. The results suggested that 7 kinds of leaf phenotypes (leaf length, leaf width, leaf petiole length, leaf area, leaf shape index, number of leaves teeth and number of secondary veins) all had plasticity. The plasticity of the leaf area was the greatest and leaf shape the least. The effect of the edaphic factor was the greatest among the environmental factors, followed by the climatic factor and the topographic factor. Weight analysis showed that total soil kalium content had the greatest effect on leaf length and area. Total organic carbon content, altitude above sea level, total phosphorus content, slope and annual precipitation had the greatest effect on leaf width, petiole length, shape index, number of leaf teeth and number of secondary veins, respectively. Five common important factors with effects on multiple leaf phenotypes including total soil kalium content, total phosphorus content, total organic carbon content, annual precipitation and slope. The membership functions of common important factors and their corresponding leaf phenotype were almost Gaussian-type and had optimum value. Achieving optimum value by manual control could promote S. sphenanthera growth. This study provided reference data for wild and ex situ cultivation of S. sphenanthera.