Alpine grasslands on the Qinghai-Tibetan Plateau play an important role in safeguarding the economic sustainability of local animal husbandry. However, these alpine grasslands have been degraded due to increased human disturbance and changing climate in the past few decades. Quantitative classification and ordination are necessary to reveal how alpine grasslands respond to the changing environments. In this study, the Two-way indicator species analysis (TWINSPAN) was used to classify 23 plots of alpine grassland communities in the Lhasa River Valley. Canonical correspondence analysis (CCA) and detrended canonical correspondence analysis (DCA) were used to clarify the geographical distribution patterns of these alpine grassland communities. Our results indicate that:(1) Alpine meadows in the study area can be classified into 8 subtypes:Elymus nutans + Tripogon bromoides; Carex moorcroftii; Kobresia pygmaea + Carex moorcroftii; Potentilla fruticose + Kobresia pygmaea; Rhododendron primuliflorum + Kobresia pygmaea; Rhododendron primuliflorum + Rhododendron nivale + Kobresia pygmaea; Rhododendron nivale + Kobresia pygmaea; and Kobresia pygmaea. (2) Each subtype identified by TWINSPAN had a specific distribution and boundaries on the DCA ordination diagram, suggesting that DCA ordination can explain the relationship between community composition and environmental factors, (3) The first and second axes of DCA reflected the influences of plot elevation and aspect, respectively, (4) CCA ordination also confirmed that altitude, followed by aspect, was the primary environmental factor controlling the distribution of alpine grassland communities, (5) The CCA of species and TWINSPAN of community subtypes were similar, indicating that the distribution patterns of the grassland community were largely affected by the species distribution pattern. Quantitative analysis is suggested to examine and assess the relative contributions of anthropogenic and natural factors to changes in the Tibetan alpine grasslands in the future.