Abstract: Characteristics of vegetation and soil inorganic nitrogen concentrations under different disturbed habitats (fenced natural grassland, unfenced natural grassland and driveways) were determined and analyzed in a weak alpine grassland ecosystem of Tianzhu. Characteristics were based on field survey for vegetation and the indophenol blue colorimetric method and dual wavelength spectrophotometry for NH4+N and NO3-N concentrations respectively. There was an obvious change between the different degrees of grassland degradation in ground plant species, coverage, height, biomass, and NO3N and NH4+N concentrations which showed a decreasing tendency in the sequence fenced natural grassland＞unfenced natural grassland＞driveway at the same soil depth. NO3-N and NH4+N concentrations decreased with soil depth in comparable disturbed habitats. From April to October NO3-N and NH4+N concentrations initially increased but then decreased and had a peak value in August. There was no significant difference in fenced soil NH4+N concentrations between August and October. In October, NO3N concentration increased in unfenced natural grassland. There were positive correlations between aboveground biomass and NH4+N, NO3-N under the three kinds of disturbed habitats.