This study quantified the effect of environmental variables on plant species composition in the Peochar Valley, located in the Hindu Raj mountains of the Hindu Kush. A mixture of quadrat and transect methods were used. Quadrat sizes were 10 × 10 m, 2 × 5 m, and 1 m² for trees, shrubs, and herbs, respectively, determined using the minimal area method. Twenty-seven stations were established along 6 elevation transects on slopes with various aspects. Density, cover, and frequency were recorded for all species in each quadrat. Aspect, elevation, rock types, soil nature, and grazing pressure were also considered as edaphic and topographic variables. Preliminary results showed that the Peochar Valley hosts 120 species. Presence/absence data for these species were analyzed with cluster and 2-way cluster techniques to elaborate species composition in the study area; this resulted in 4 plant communities. Species abundance and environmental data matrices were developed to evaluate the ecological gradient of vegetation through canonical correspondence analysis. Of the environmental variables, elevation, aspect, grazing pressure, soil depth, and rock type showed a significant effect on species composition and diversity. We also identified the dominant and rare plant species in each plant community based on their low importance value indexes. Conservation measures are recommended for all flora of this valley and for rare species in particular.