The increasing of land conversion in Manado, North Sulawesi, such as reclamation, tremendously influence mangrove functions. Therefore, conservation in this area are needed to restore its condition. Mangrove structure and composition inventory based on vegetation analysis method is an early step of conservation. This study is aimed to determine the structure and composition of mangrove vegetations in Manado, North Sulawesi Province. This baseline study hopefully can be considered for policy making, monitor changes in environmental conditions, and conserve mangrove ecosystem in Indonesia. This research used descriptive and explorative methods, while vegetation data were collected by purposive sampling method and plot sampling on each transect. Samples were collected by stratified random sampling. This study found 5 types of mangroves inside transect areas which are categorized as mayor mangrove. In general, mangrove vegetations in Manado are dominated by Sonneratia alba. Tree category of Diversity Index (H') and Uniformity (J') in Manado is low category. The height of mangrove trees in this area are dominated by class of 5 - 10 m.