Leaf functional traits can most reflect the sensitivity of plant growth to the environmental changes, and can thus be used to predict the recovery ability of plants after grazing disturbance to some extent. In this study, we explored the effects of water and nitrogen (N) addition on changes of several leaf functional traits of the dominant species, Stipa breviflora, in a desert steppe at a grazing experimental site with control of grazing intensity. Our objectives are to uncover the adjustment of increasing water and N supply to some functional traits of S. breviflora under different grazing intensities. The results showed that N and water addition significantly increased foliar N concentrations and decreased leaf carbon to N ratio (C/N) of S. breviflora. The grazing intensity also significantly increased foliar N concentrations. The foliar N concentration under light grazing (20.36 g/kg) was significantly higher than that under control (18.80 g/kg). The specific leaf area, leaf C concentration, C/N ratio, and C/phosphorus (P) ratio of S. breviflora at the end of growing season were significantly higher than those at the peak of growing season, while the leaf N and P concentrations at the end of growing season were significantly lower than those at the peak of growing season. The addition of N and water, either alone or combined, was also different under different grazing intensities at the peak and end of growing. Our study showed that the leaf N concentration of S. breviflora increased with N and water addition under different grazing intensities, especially increased the leaf N and P concentration at the end of growing season, which can further promoted the growth of S. breviflora. The results also indicate that the improvement of resource supply is helpful to rapid recovery of S. breviflora under different grazing intensities.