Indian part of Sunderbans is a wide area spread between the rivers Matla in the west and Roymangal in the east. The Mangroves are unique intertidal ecosystem that supports the biodiversity in a wide band. The brachyuran crabs prefer mangroves to complete their biological cycle and along with the crabs, shrimps, prawns, lobsters are also found to be abundant in the mangrove creeks. The present study is an attempt to 􀏐ind the occurrence of some eco-sensitive species and to access the diversity loss. The eco-sensitive crab species acts as eco indicators. The present study mainly focused on the distribution and diversity of Brachyuran crabs in Sunderbans. The brachyuran crabs were collected from different ecosystems. It was collected from mud by hand-picking and using forceps. Crabs were counted with their holes within the area and accessed. The diversity and distribution of the crabs were examined along the coast and mangrove areas of different ecosystems. The GPS points were made using GARMIN 12 channel GPS. The present study resulted with the collection of 405 examples of brachyuran crabs comprises of 06 families, 07 genera and 14 species. All the species were taxonomically analysed and their distribution is illustrated. The ecological analysis resulted with the abundance of brachyuran crabs are more in the mangrove areas compared with the mud 􀏐lats of Sunderbans. Comparatively the Ocypode crabs were found to be abundant on the disturbed Bali Island. Studies were limited on the diversity, abundance and dynamic pattern of the brachyuran crabs in Sundarbans hence the present study undertaken. The mode of adaptation and successful completion of life cycle determines the species richness in the respective habitat. The Anthropogenic threats played a major role to change both the sandy beach and island ecosystem from vulnerable to endangered. Rapid increase of human population and solid constructions is the growing threat to not only to Gangasagar and Bakkhali but also to the entire Sundarbans.