Research on the level of damage to mangrove ecosystems has been carried out in Estuarine Area Sei Jang. The purpose of this study was to determine the types of mangroves, the density and percentage of mangrove canopy cover, and the level of damage to mangrove ecosystems in the Sei Jang Estuary Area of Tanjung Pinang City. This research was conducted in March 2019. Determination of the research location using a purposive sampling method of 3 stations and using a 10 x 10 m transect for the density and percentage of mangrove canopy cover. The results found four types of mangroves namely Bruguiera gymnorhiza, Rhizophora apiculata, Rhizophora mucronata, and Ceriops tagal with density values (1.033-1.367 individu/ha) and the percentage of mangrove canopy cover with values (61.55-78.41%). For the level of damage at Station I and III are categorized (good) and Station II is categorized (Damaged).