Merapi is an active volcano to date, naturally generated eruptions can change the diversity of vegetation due to changing environmental conditions, climate and soil material. This study aims to identify vegetation diversity and analyze the composition composition and shape of tree vegetation structures in the upper slope area on the southern slope of Mount Merap This research was conducted by survey method, then analyzed to determine the value of Density, Frequency, Domination, Important Value Index, and Diversity Index (Shannon-Wiener). The results of the analysis show that the Upper Slope Area on the South Slope of Mount Merapi is composed of 14 species and 54 individuals. The Kaliadem Study Area has a Low Diversity Index with a value of 0.58. While Palemsari and Kalitengah Lor have a Medium Diversity Index, each with values of 2.07 and 1.39.