The study on characteristics of plant communities and their environmental factors along the environmental gradient remains an important topic in ecological research. The Yarlung Zangbo River is one of the highest rivers on earth, and the most important river in Tibet. There was no systematic study on the plant community of P. centrasiaticum in its basin. In this study, 26 sampling sites were set up in the main distribution area of P. centrasiaticum from Payang Town, Zhongba County, the source area of the Yarlung Zangbo River, to Pai Town, Milin County, the middle reaches of the Yarlung Zangbo River to investigate the characteristics of P. centrasiaticum communities. The results showed that (1) a total of 119 plant species belonging to 35 families and 96 genera in the distribution area of P. centrasiaticum mainly included Compositae, Gramineae and Leguminosae. The dominant species in these sample sites were P. centrasiaticum, Sophora moorcroftiana, Artemisia wellbyi, Artemisia sacrorum and Orinus thoroldii. The average richness in P. centrasiaticum communities was 22.04, ranging from 12 (Sangri county) to 37 (Gyantse county), and the average importance value of P. centrasiaticum was 39.38%, ranging from 11.88% (Sangri county) to 67.52% (Lhatse county). (2) The average underground biomass of 26 P. centrasiaticum communities was 3374.23 g/m², and the percentage of the underground biomass in the 0-10 cm, 10-20 cm and 20-30 cm soil layers of P. centrasiaticum communities were 60.38%, 26.36% and 13.26%, respectively. (3) The significantly negative correlations (P<0.01) were detected between altitude and height of P. centrasiaticum (r=-0.60), soil pH and height of P. centrasiaticum (r=-0.53), soil pH and biomass of P. centrasiaticum (r=-0.55). (4) Redundancy analysis (RDA) showed that axis 1 and axis 2 explained 40.60% of the total variance, and played a leading role in the explanation of environment-P. centrasiaticum communities. Among them, the RDA1 axis showed a strong relationship with soil pH, precipitation, soil total nitrogen content (TNC), soil alkaline nitrogen content (ANC), soil available phosphorus content (APC), soil organic carbon content (SOC), and soil moisture, which explained 23.30% of the variance. It also revealed that soil nutrient factors and precipitation influenced the structure of the P. centrasiaticum communities. The RDA2 axis showed a strong correlation with temperature and total phosphorus content, which explained 17.3% of the variation. (5) Cluster analysis of altitude data in distribution area of P. centrasiaticum was conducted, and the sample sites in the upper and middle reaches of the Yarlung Zangbo River could be divided into altitude gradient Ⅰ (3008.67 m), altitude gradient Ⅱ (3824.75 m), and altitude gradient Ⅲ (4419.29 m). In the three altitude gradients, the height of 4 functional groups (Gramineae, Leguminosae, Compositae and Weeds) were decreased with altitude, the Gramineae functional group possessed the largest height, coverage and importance values in different altitude gradients. The species richness and percentage of underground biomass increased with altitude. The results showed that P. centrasiaticum was widely distributed in the upper and middle reaches of Yarlung Zangbo River Basin, and the characteristics of P. centrasiaticum communities showed strong correlation with environmental factors.