This study was conducted in Magada Forest, Bule-Hora District, Borena Zone, Oromia Region, Southern Ethiopia. The main objective of the study was to investigate diversity and vegetation structure of trees and shrubs in the forest. Systematic sampling method was used to collect vegetation data. Accordingly, 35 quadrats, each with 20 m x 20 m (400 m2) were laid along line transects at the distance of 100m from each other. The plant species were collected, brought, identified and deposited at the National Herbarium (ETH), Addis Ababa University. Data were analyzed using different software such as Microsoft Excel, Shannon-Wiener diversity index, TWINSPAN and PAST. A total of 38 plant species belonging to 23 families and 27 genera were recorded and identified. Family Asteraceae had the highest number of individuals 227 followed by Celastraceae 221 and Apocynaceae 217. The forest was dominated by small sized trees and shrubs indicating that it is in the stage of secondary regeneration. The vegetation is disturbed because of many factors including grazing and browsing by livestock and other humans’ activities. These further retards diversity and vegetation structure of the forest. Therefore, based on the results, to protect and conserve this forest appropriate management strategy and awareness creation for the local people on the wisely use is very important. The maintenance of biodiversity that promote sustainable use of the forest and its products are also recommended.