The proportional relationships of nutritional elements with plants, soil, and the environment have been studied intensely. Relationships that occur along continuous environmental gradients should be analyzed to better understand these issues. There are obvious differences in plant and soil types at different points along the hydrothermal gradient, which provide a unique advantage to examine the vertical spectrum of plants and soil ecological stoichiometry. In this study, we examined organic carbon (C), total nitrogen (N), and total phosphorus (P) in plant and soil samples collected along the altitude gradient of the north slopes of the middle Tianshan Mountains (the altitude of which varies from 1000 to 3840 m). The results showed that (1) with increasing altitude, C, N, and P content and the stoichiometric ratios in plants leaves differed. C levels were almost invariant, and only the mountain needle leaf forest had significantly lower C levels than the subalpine shrub meadow, alpine cushion vegetation, and piedmont scrub (P<0.05). Second, N content and C:P and N:P ratios first increased and then decreased with altitude, and levels in the mountain needle leaf forest and subalpine shrub meadow were significantly higher than in the mountain desert steppe, mountain steppe, and alpine cushion vegetation (P<0.05). Finally, P content and C:N ratio first decreased and then increased with altitude, and were significantly higher in the alpine cushion vegetation than in the other vegetation types. Moreover, levels in the mountain desert steppe, piedmont scrub, and alpine meadow were significantly higher than in the mountainous steppe, mountain needle leaf forest, and subalpine shrub meadow (P<0.05). (2) There was no significant difference in C content among trees, shrubs, and herbs, and this also true for N and C:N ratio. However, P levels and C:P and N:P ratios were significantly higher in shrubs than in herbs (P<0.05). Trees and shrubs were largely limited by P, and herbs were limited by N. (3) With increasing altitude, soil C, N, and P content and the C:P and N:P ratios first increased and then decreased, and were significantly higher in mountain needle leaf forest and subalpine shrub meadow than in mountain desert steppe and mountainous steppe (P<0.05). The C:N ratio decreased with altitude, and was significantly higher in the mountain desert steppe than in the other vegetation types (P<0.05). (4) Plant C:P ratios were significantly correlated with the soil C:P ratio, and the correlation coefficients of plant and soil C, N, and P content were less than that of the plant stoichiometric ratio and soil. These results suggest that plants are mainly influenced by soil through stoichiometric ratios in the vertical zone.