This study aimed to investigate the diversity and distribution pattern of tree in different altitudes in a protected area of Churdhar Wildlife Sanctuary (CWS), situated in Himachal Pradesh, Western Himalaya, India. CWS is one of the famous sanctuaries and rich in biodiversity. The tree species analysis was done with the stratified sampling technique by performing a random sampling using the quadrats method. The study area was divided into four different altitudes: (i) Chhogtali (CT; 1900–2200 masl), (ii) Churas (CH; 1900–2200 masl), (iii) Nohra 1 (NH1; 2800–3200 masl), and (iv) Nohra 2 (NH2; 2800–3200 masl). Among the studied sites, results revealed that tree species richness decreases with an increase in altitude. Quercus leucotrichophora was dominant in CT and CH sites, whereas Q. semecarpifolia was dominant in NH1 and Abies spectabilis in NH2 sites. Picea smithiana reported to be dominant species in the studied sites. Compared to CT and CH sites, the dominance-diversity (d-d) curve showed a decrease in species richness on HN1 and NH2 at higher altitudes, whereas tree total basal cover (TBC) increases with altitude. The maximum similarity was between CT and CH sites and reduced between CT and NH2 sites with higher altitudes. Almost all tree species exhibited contagious distribution patterns which are common in natural forests; however, a few species showed random distribution, and no species were found distributed regularly. This study provides fruitful information to the policy-makers, environmentalists, and foresters to understand species diversity and distribution with species composition and structure with altitude. Thus, conservation and sustainable management strategies of the forest could be design in better ways to conserve diversity on a regional and/or global scale.