A plant life-form in a particular ecosystem is the sum of its all life processes and evolved directly in response to the prevailing environment. It is considered as a potential indicator of phytoclimatic conditions of the ecosystem in which it populates. The spatial distribution patterns of life-forms vary from one ecosystem to another due to variation in the environmental gradients. The present study was aimed to assess the distribution patterns of different life-forms along the altitudinal gradients in the Great Himalayan National Park (GHNP) situated in Kullu district of Himachal Pradesh (Western Himalaya, India). We prepared a checklist of flowering plants of the park (945 taxa, 470 genera, 188 families) using both primary (field surveys) and secondary data (earlier published literature) sources. The entire altitudinal range was classified into seven altitude classes. The presence/absence (1/0) species data matrix was prepared using local altitudinal distribution range of each species to investigate the similarity in species composition and patterns of life-forms across the seven altitudinal classes. The Cluster analysis classified the seven altitudinal classes into four distinct plant communities at different altitudes. Maximum similarity (43.77%) in species composition was recorded between 3000–3500 m and 3500–4000 m altitude classes. In terms of number of species, Asteraceae (101 taxa) and Potentilla (11 taxa) revealed as dominant family and genus respectively. The species richness peaks at middle altitude (1500–3000 m) in the GHNP. The phytoclimate of GHNP can be termed as ‘phanero-therophytic’ (<1500 m), ‘thero-phanerophytic’ (1500– 3000 m) ‘thero-hemicryptophytic’ (3000–4000 m) and ‘crypto-hemicryptophytic’ (>4000 m) at different altitudes. © 2020, College of Life Science. All rights reserved.