The present study quantifies the diversity and composition of tree species having girth size > 15 cm in the tropical forests of Darjiling part of Eastern himalaya through nested quadrat sampling method. In total, 74 species under 64 genera and 36 families were recorded. The individual density varied from 25 to 88.89 individuals ha-1. Shannon-Weaver Index ranged from 0.016 to 0.138 whereas the species richness varied from 0.074 to 0.894. The most dominant families were Lauraceae and Malvaceae, followed by Leguminosae and Phyllanthaceae. The abundance to frequency ratio ranged from 0.020 to 0.125 and the basal area ranged from 0.088 ±0.003 to 76.172 ±0.285m2 ha-1. The dominant species was Shorea robusta (IVI: 27.502) followed by co-dominant species Tetrameles nudiflora (IVI: 15.998) and Tectona grandis (IVI: 11.442). The study reveals that the favourable climatic condition is one of the reasons for the rich diversity and composition of the tree species in the area.