Study of Grass species diversity was conducted under humid and tropical climatic condition in Mizoram University Campus, western part of Aizawl, Mizoram, India. A total of 22 species under 19 genera of 2 families of grass were collected and identified. The study area falls under the tropical semi-evergreen forest and was divided into two experimental sites on the basis of disturbance gradients; disturbed site harboured 22 species, 19 genera and 2 families whereas in undisturbed site 4 species, 3 genera and 2 families were observed. Taxonomically, Poaceae was the dominant family in the study area. The most dominant grass species with highest Important Value Index (IVI) in disturbed site and undisturbed site were Imperata cylindrica (Linn.) Reuschel and Ichnanthus vicinus (Bail.) Merr., respectively.