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A case study on the richness variation of vascular plant species along the climatic gradient from mountain foot (400 m asl) up to the summit (3,100 m) was carried out in Mt. Shennongjia of central China. The results show that climatic features such as mean annual temperature ( Y = 16.26 - 0. 506X, R2 = 0. 995), mean annual precipitation ( Y = 235.48 + 82. 663X, R2 = 0. 951) and frost-free day ( Y = 283.54 - 7. 148X, R2 = 0. 964) are linearly responding to the elevational increase. However the variation of species richness is not uniformly linearly correlated to the climatic gradients. From 400 m up to 1,000 m, the species number increases from 933 to 1718, with a increase rate of 126.18 species/100 m (R2 = 0.951, P<0.001). From 1,000 m up to the highest peak of 3,100 m, species richness gradually declines with a rate of 94.36 species/100 m (R2 = 0. 961, P<0. 001). This variation can be described by a cubic model, y = - 458.22 + 463.93 x - 30.64 x2 + 0.53 x3 ( R2 = 0. 989, P < 0. 0001 ). Analysis calls for further study for better understanding of the relationship between biodiversity and environmental variation in this key area.