Study area Sylhet, situated in the northeastern region of Bangladesh, supports a considerable portion of the country’s forest lands with diversified landscapes including plain lands, hills, reed lands, and fresh water swamp depressions. Sylhet Forest Division laying between 23°55’-25°12’ north latitude and 90°55’-92°30’ east longitude, consists of 46,976 hectares reserve forests, 4,426 hectares acquired forests, 2,160.97 hectares Unclassified State Forest (USF) and 24,109 hectares proposed reserve forests. The whole region is rich in floral diversity including herbs, shrubs, trees, climbers, bamboos, canes, reeds, grasses, and epiphytes (Patwary, 1999). Sylhet is located on the northern bank of the Surma River. The physiography of Sylhet comprises mainly of hill soils, encompassing a few large depressions known locally as “beels”. The Sylhet Forest Division is extended over four districts, namely Sylhet, Sunamgonj, Moulvibazar, and Hobigonj under the central circle of the Forest Department. For this research work, the primary data was collected from early October 2009 to late January 2010. The present study was conducted in two phases namely, topographical site selection and sample plot selection. Data collection from the topographical strata namely top of the hill, middle of the hill and plain land was carried out at the first phase and sample plot selection at the second phase. Sample plot selection Total 45 sample plots, 15 from each location, were randomly selected for study. The optimum quadrate size of 2 m × 2 m circular was determined as it minimize the edge effect of taking sample plots. Primary data was collected about invasive species status, and composition, such as counted number of herbs, shrubs, vines, etc. and recorded this for further analysis. The main objective of this survey is to explore the status, diversity, and richness of the invasive species in the Khadimnagar National Park area. Quantitative analysis Within each plot, the number and name of all the plants were counted and recorded. Different species in the area have been gathered and representative samples have been collected for herbarium preparations. The collected specimens were identified following Prain (1903), Brandis (1906) and Heinig (1925) and local people and taxonomist. Density, relative density, frequency, relative frequency, abundance, and Importance Value Index (IVI) were calculated through Shukla and Chandal (2000) and Dallmeier et. al., (1992). In the present study, five diversity indexes were analyzed to get a clear picture of invasive plants diversity of the study area.