Nitrogen (N) resorption from senescent leaves has long been recognized as an important mechanism by which plants can effectively use soil nutrients and adapt to their environments, particularly under arid and infertile conditions. Many studies have shown that N resorption capacity is controlled by N contents in the soil or vegetation, which is influenced by precipitation. There exists a remarkable precipitation gradient (ranging from less than 100 mm to 700 mm) from the west to east on the Changtang Plateau, where the climate is highly cold and dry and soil nutrients are poor. To better understand the N use characteristics along a precipitation gradient in the alpine nutrient-poor environment, we investigated leaf N resorption strategies of a dominant plant species, Stipa purpurea and their correlations with environmental factors on the Changtang Plateau in Tibet. Green and senescent leaves of S. purpurea and soil samples were collected along the precipitation gradient in July and October 2014. Nitrogen resorption efficiency (NRE, relative reduction in N between green and senescent leaves) and N resorption proficiency (NRP, absolute reduction in N in senescent leaves) were calculated, and the relationships between NRE, NRP, N contents, and climate were determined. Stipa purpurea had higher leaf N concentration and NRE along the precipitation gradient. The average green leaf N concentration of S. purpurea was (23.87 ± 3.92) g/kg in the growing season, which was higher than the mean levels across China (20.9 g/kg) and the world (20.1 g/kg). The leaf N concentration, which was higher in the west than in the east of the plateau, was closely correlated with mean annual precipitation (MAP). The average NRP was (6.76 ± 1.42) g/kg. The mean NRE was (71.25 ± 6.46)%, which was considerably higher than the counterpart both in the Chinese temperate grasslands and in grasslands worldwide (46.9%-58.5%). The N levels of senescent leaves were among the key determinants of NRE. High levels of N resorption from senescent leaves were the internal basis for high NRE. NRE was significantly correlated with MAP, soil total N (TN), and soil inorganic N; NRP was only related with soil inorganic N, but not with TN and MAP. The NRP and NRE were not related to leaf N concentrations, although both were negatively correlated. The influence of mean annual temperature and altitude on NRE and NRP was not significant. Therefore, high NRE and low NRP of S. purpurea might be indicators of N conservation in the arid and nutrient-poor environment. Internal N cycling through N resorption might have reduced N loss. Our findings suggest that soil N availability is a key controlling factor for the N resorption capacity of S. purpurea along the precipitation gradient on the Changtang Plateau, and that precipitation has an indirect effect on NRE by influencing soil N availability and green leaf N concentrations.