Aim <p>Biomass allocation in grassland is key to understanding plant response to environmental changes for predicting the dynamics of ecosystem processes. However, global studies on biomass trade-off along degradation degree and its regulatory factors are notably scarce.</p> Methods <p>In this study, four plots, intact (ND), lightly degraded (LD), moderately degraded (MD) and heavily degraded (HD) in the Tibetan Plateau, were selected to analyse biomass allocation, soil characteristics, and biomass trade-offs, and clarified the biomass trade-offs and its driving factors.</p> Results <p>The results showed that: 1) above- and below-ground biomass showed a decreased trend along degradation gradient compared to original vegetation, the community aboveground biomass and 0–30&#xa0;cm belowground biomass were highest in ND site with 233.8&#xa0;g&#xa0;m⁻² and 1775.9&#xa0;g&#xa0;m⁻², respectively; 2) the biomass trade-offs in the degraded and intact grasslands is consistent with the hypothesis of optimal partitioning, and high proportion of biomass was allocated to shoots in ND, LD, MD and HD site, with trade-off index of 0.018, 0.022, 0.009 and 0.037, respectively. 3) soil catalase, soil organic matter, and soil alkaline phosphatase had directly negative effect on the biomass trade-offs, soil total phosphorus and soil available phosphorus had exerted a directly positive influence on the biomass trade-offs. 4) soil total phosphorus is the main factor determining biomass trade-offs among different degraded degree alpine grassland.</p> Conclusions <p>Our research revealed biomass trade-offs among different degraded degree alpine grassland, and provided a foundation for refining restoration management strategies in ecological restoration of the Qinghai-Tibetan Plateau.</p>