Background: Plant growth is often water limited in drylands, and it has been proposed that alleviation of this resource stress by future increases in reactive precipitation may affect internal plant nutrient cycling, thus influencing grassland ecosystem productivity. Methods: A 4-year field experiment was performed to examine the effects of water reduction and addition on nutrient concentrations in soil and plants. We studied five dominant plants in Stipa breviflora desert steppe in Inner Mongolia, and through a simulated precipitation experiment, measured the changes in plant leaf nitrogen (N) concentration, nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE) natural precipitation, 50% water reduction, 50%water addition and 100% water addition. The effects of different water treatments on nutrient resorption efficiency and its influencing factors were analyzed. Results: Compared with natural precipitation, 100% water addition significantly increased soil moisture and significantly decreased soil available nitrogen. The aboveground biomass of the grassland ecosystem was significantly increased, and the nitrogen and phosphorus concentrations in green and senescent leaves were reduced, thus reducing NRE and PRE. NRE was significantly negatively correlated with N concentration in senescent leaves, and PRE was significantly negatively correlated with phosphorus concentration in senescent leaves. Conclusions: Water addition dilutes the nutrient concentration of plant leaves by increasing aboveground biomass, resulting in the reduction of plant nutrient resorption efficiency. Dominant plants are resistant to nutrient poor habitats in the desert steppe of northern China.