The alluvial fan is a precious land resource in Lhasa River Basin, and knowing its soil nutrient status is the basis for its scientific development and utilization. In this study, ten alluvial fans in the Lhasa River Basin were selected as sample plots, where the plant community composition was investigated and soil was collected from July to August, 2020. The soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP) and available potassium (AK) contents were determined by the soil samples and taken to calculate measurement ratio. The results showed that 87 plant species were found in this research, belonging to 79 genus and 29 families, among which the Gramineae and Compositae plants were the majority. The average contents of SOC, TN, TP, AN and AK were 34.38 g/kg, 2.77 g/kg, 0.39 g/kg, 130.78 mg/kg and 189.79 mg/kg respectively, which all were showed grassland>shrubland>farmland, where SOC, TN, AN and AP were significantly different under grassland and farmland (P<0.05). The average content of TK was 19.68 g/kg, which was showed farmland>grassland>shrubland. The average content of AP was 3.36 mg/kg, which was showed farmland>shrubland>grassland. The average value of C:N was 12.75, which was showed farmland>shrubland>grassland. The mean values of C:P, N:P and N:K were 102.50, 8.10 and 0.16, respectively, which all were showed grassland>shrubland>farmland. Generally, P element was scarce in alluvial fan soil. There were significant correlations between soil N:K and SOC, TN, TP, TK, AN, AP, AK, and the community coverage was significantly correlated with SOC and TN (P<0.01), while the Shannon-Wiener diversity index, Margalef richness index, and Pielou evenness index showed no correlations on the SOC and TN. Additionally, Correspondence Analysis (CCA) showed that soil nutrients and their stoichiometric ratios had significant effects on species composition of plant communities in the alluvial fan (P=0.002), and TP, K:P, AP were the dominant factors of the composition of plant communities. In conclusion, the species of alluvial fan plants in Lhasa River Basin were relatively abundant, but the distribution was uneven and the composition was unstable. The contents of SOC, TN and TK were relatively high, but the C:N values were relatively low, indicating a high rate of soil organic matter mineralization and low soil fertility. Moreover, TP and AP contents were low, the plant community of alluvial fan was limited by soil P element in the process of growth and development. Furthermore, it was also found that soil N:K could be used as a soil ecological stoichiometric indicator to evaluate soil nutrient status as C:N:P.