In Chinese grassland transect which across Inner Mongolia and Qinghai-Tibet Plateau,132 sampling plots were set up,and 329 leaf samples which belong to 138 species were collected. Based on the chemical analyses of plant samples, the spatial pattern of leaf nitrogen and phosphorus elements and its related to climatic factors were analyzed. The purpose of the study was to provide the basis for the researches of grassland C,N and P element cycles and grassland ecosystem response to global climate change, and also provide basic data for ecological model. Results showed that plant N and P contents in Qinghai-Tibet Plateau region were higher than those in Inner Mongolia area. The N content of plant leaf decreased, whereas P content and N/P ratio did not change significantly with the increase of mean annual temperature. The N and P contents of plant leaf slightly increased,while N/P had no obvious change with the increase of mean annual precipitation. These results proved a temperature - plant physiological hypothesis, and also supported a soil substrate age hypothesis and a growth rate hypothesis. However,The pattern, rule and mechanism of N and P in grassland vegetation needed further study.