[Objective] The response of carbon, nitrogen and phosphorus of each component (plant leaves, roots and soil) of grassland community to precipitation change was studied, in order to reveal the influence of precipitation on the stoichiometric characteristics of grassland ecosystem in loess hilly region.[Methods] The natural restored grassland in loess hilly region was taken as the research object, a field rain control test platform was established at Ansai experimental station during 2017-2018, with 7 treatments including 60% rain reduction, 40% rain reduction, 20% rain reduction, natural precipitation, 20% rain increase, 40% rain increase, and 60% rain increase. The canopy method was adopted to study the influence of precipitation change on the leaves, roots and soil ecological stoichiometric characteristics of plants.[Results] ① With the increase of precipitation, the water restriction in plant growth was effectively alleviated, and the effect of water stress gradually slowed down, so that the N and P contents in leaves showed a significant decline (p<0.05). And the C/N and C/P of the leaves also showed a significant downward trend (p<0.05). ② The change of precipitation gradient had a significant effect on the P contents of root system (p<0.05). The change of precipitation gradient had significant influence on root C/P and N/P (p<0.05). ③ Rain control treatment only had significant effect on soil C content (p<0.05), which may be because extreme precipitation affected the activity of soil microorganisms, resulting in a slow accumulation of soil organic C.[Conclusion] Water is the limiting factor for the absorption and utilization of N and P by grassland plants in loess hilly region. Precipitation can change the nutrient restriction pattern of grassland community. With the increase of precipitation, plant growth is more restricted by P, and plant growth will changed from being restricted by both N and P to being restricted by P.