In order to investigate the relationship between leaves carbon (C), nitrogen (N) and phosphorus (P) contents and environmental factors in different vegetation types on the eastern slop of Helan Mountains, we selected five typical vegetations including alpine meadow (Ⅰ), pure forest of Picea crassifolia (Ⅱ), pure forest of Populus davidiana(Ⅲ), shallow shrub (Ⅳ) and desert grassland (Ⅴ) along the elevation gradient. The contents of C, N and P in the leaves of 63 plant species and soil nutrient characteristics in sample plots were determined. The relationship between the C, N, and P contents and their stoichiometric characteristics of plant leaves and the environmental factors were investigated. The result showed that: (1) Based on the 63 plant species on the eastern slop of Helan Mountains, the average leaf C, N and P contents were 520.46±62.08 mg·g^-1, 24.03±3.37 mg·g^-1 and 1.69±0.51 mg·g^-1, respectively. Leaf N, P, C/N, C/P and N/P had a normal distribution (P>0.05), while leaf C did not conform to positive distribution (P<0.05). Leaf C/N and N/P were more variable than C/N. (2) Leaf stoichiometric characteristics in different life forms had significant difference. Trees had the highest leaf C and P contents, while the herbs had the highest leaf N content. The trees had the highest C/N and lowest N/P, while the shrubs had the highest C/P. (3) The leaf N, N/P, and C/P were increased with the altitude rising, only decreasing at 2 073 m (pure forest of P. davidiana). Leaf P and C/N reached peak at 2 073 m, then decreased with altitude rising. (4) Our results suggested that desert grassland, shallow shrub were subjected to P, while the pure forest of P. crassifolia was limited by N. The alpine meadow was limited by N and P, although N/P of pure forest of P. davidiana was under 14, the high absorptivity of N and P rejected the N limitation.