Leaves and roots are the most important organs for plants to acquire resources. Trait variations across environmental gradients reflect photosynthetic carbon acquisition, the water and nutrient absorption capacity of plants, and their ecological strategies for adapting to environmental changes. Studying leaf and root pairwise traits of alpine grassland communities along a precipitation gradient on Changtang Plateau can not only reveal the shaping effect of environmental gradients on plant traits but also provide a basis for understanding the adaptation strategies of plants in extreme environments such as cold, drought, and barren land. Therefore, we selected three representative pairwise leaf and root traits:specific leaf area (SLA) and specific root length (SRL), unit mass leaf nitrogen content (LN_mass) and unit mass root nitrogen content (RN_mass), leaf nitrogen content per unit leaf area (LN_area) and root nitrogen content per unit root length (RN_length), to analyse the variation in characteristics of above-ground and below-ground pairwise traits of different dominant plants and their relationship with environmental factors. We also explored the adaptation strategies of plant traits to water and nutrient limitations in alpine ecosystems. The results showed that variations in leaf traits caused by regional climate and soil environments were greater than those in root traits. The plants at the dry end had both high SRL and high nutrient contents in the leaves and roots (LN_mass, LN_area, and RN_mass). The SLA-SRL, LN_mass-RN_mass, and LN_area-RN_length all showed a trade-off relationship, especially in the alpine steppe and desert steppe at the dry end (annual rainfall MAP < 400 mm), and alpine meadow under extremely humid conditions (MAP > 600 mm). However, in the middle region (400 < MAP < 600 mm), nutrient and water limitations in the alpine meadow were not very strong, and the leaf and root traits showed a more coordinated relationship. From the perspective of plant functional groups, there was a stronger trade-off between the pairwise traits of the leaves and roots of sedges and grasses. The drought-end plants increase the absorption capacity of water and nutrients by increasing the SRL and leaf and root nutrient contents, meanwhile increasing the photosynthetic carbon acquisition capacity through the high nitrogen content of the leaves. This ensures the source of root growth, showing strategies for simultaneous investment in both above-ground and below-ground. It is an important strategy for drought-end plants to maintain high nutrient content to resist and adapt to severe cold, drought, and barren environmental stress, while for plants at the humid end, the ecological strategy is to increase SLA and maintain above-ground photosynthetic productivity.