Mount Sekincau is a part of Bukit Barisan Selatan National Park (BBSNP) that has less been explored. It is situated at between 1100 to 1719 m above sea level. This area included in the category of lower montane rain forests. A vegetation analysis has been conducted to determine the tree structure variation and composition of trees in Mount Sekincau BBSNP. Sample plots were randomly chosen (purposive random sampling) at five locations which consist of 10 plots sized 50 x 50 m2 (0.25 hectares). There were 32 families 59 genus and 89 species with a density of 253 ind/0.5 ha. Mount Sekincau area has an airly good condition, this is indicated by the average value of diversity index (2.67) and evenness index (0.47). Trees often found in this area are members of family Lauraceae, Fagaceae, Euphorbiaceae, Dipterocarpaceae, Myrtaceae and Rubiaceae. Quercus blumeana Korth. (kayu pasang) is dominating and important species (IVl = 27.18%) and has a wide distribution in Sekincau. The forest in this area has an important role to support life and the environment. Therefore, managers of BBSNP can improve care and maintenance. Moreover, Sekincau area directly adjacent to residential areas, so that the necessarily sustainable management on an ongoing basis to meet the needs of the surrounding community.