Pattern of biodiversity along environmental gradients is one of the basic issues in the biodiversity studies. The environmental gradients include several factors, such as elevation, water and thermal conditions, anthropogenic impacts, and so on. Especially the altitudinal gradient incorporates multiple resource gradients which vary continuously differently. This study was conducted in the Yiluo river basin, straddling Henan and Shanxi Province (109°43'-113°10'E, 33°39'-34°54'N), ranging from 101 m to 1227 m. The Yiluo River is an important tributary of Yellow River in the south side of the middle reaches. The vegetation in drainage basin ecosystem of Yiluo River has been heavily impacted by human. In this research, we focused on the herb communities in different habitats formed by different disturbance types and intensity along different environmental gradients in the drainage area of the Yiluo River. A field investigation was conducted in August and September of 2009, to describe the distribution patterns and the abundance features of the species in different habitats, from two aspects, alpha diversity and beta diversity, the altitudinal gradient distribution pattern of the herb biodiversity and its environmental explanation. This study explored the influence of human and natural disturbance on the distribution patterns of species within the drainage area, with purposes of offering a scientific guidance to the restoration of the biodiversity in the herbs communities, the management of the watershed and the evaluation of its ecological environment, so as to promote the sustainable use and harmonious development of the watershed eco-system. Using community ecology techniques, we sampled 134 20 m×20 m plots. Each plot consisted of five 1 m×1 m quadrats (the four corners and the center). We recorded the frequency, density, coverage, height and phenophase of plant species present in the quadrats, as well as ecological conditions of the sampling sites. The results of this study show that: both Patrick richness index and Shannon-Wiener diversity index were slightly S-shaped curve shaped; plant community types did not differ markedly in the distribution pattern of alpha diversity; the species abundance and species diversity were higher in the hilly regions of the river's middle reaches, and lower in the plains of the river's lower reaches; the beta diversity had a similar distribution pattern to alpha diversity; species replacement rates were higher in the hilly regions and lower in the plains. The upper reaches were largely covered by natural vegetation; with light anthropogenic disturbance, relatively high species diversity, and stable species replacement rate; the distribution of a species was mainly constrained by its competitiveness and dispersal ability, as well as habitat conditions. The intensively farmed lower reaches were dominated by agricultural ecosystems; species compositions were simple, while species replacement rates could be abrupt, and species distributions were mainly influenced by human activities. The hilly transition zone of the middle reaches was under moderately intense anthropogenic disturbance, natural and accessory plant species grew together in the mixed communities, with relatively high species diversity and replacement rate. To sum up, the pattern of herbaceous species diversity in the Yiluo river basin was strongly influenced by human activities, with high species replacement rate.