Six field trips were conducted to assess the species composition and size structure of sea cucumbers at Nam Du Island, Kien Giang province, Vietnam from March to December 2018. Numerous sites covering different depths (1-30 m) and habitats (intertidal flats, sea grass beds, rocky beds, and coral reefs) were done during the night by walking and snorkeling diving for collecting sea cucumbers. A total of 389 harvested samples, 14 species were found from two families such as Holothuriidae (8 species) and Stichopodidae (6 species). The most dominant species found around the island was Holothuria leucospilota (32.13%) followed by Pearsonothuria graeffei (31.11%) and Stichopus variegatus (17.22%). Conversely, the high commercial species (H. fuscogilva, H. nobilis and H. scabra) occupied a negligible quantity (