The study analyzed the composition of the aquatic invertebrate fauna of Song Thanh Nature Reserve in Quang Nam province of Vietnam. This investigation was realized in March and September 2015. | VNU Journal of Science: Natural Sciences and Technology, Vol. 33, No. 3 (2017) 56-65 Aquatic Invertebrate Fauna of Song Thanh Nature Reserve in Quang Nam Province, Vietnam Ngo Xuan Nam*, Nguyen Thanh Trung Institute of Ecology and Works Protection, 267 Chua Boc, Dong Da, Hanoi, Vietnam Received 14 August 2017 Revised 8 September 2017; Accepted 12 September 2017 Abstract: The study analyzed the composition of the aquatic invertebrate fauna of Song Thanh Nature Reserve in Quang Nam province of Vietnam. This investigation was realized in March and September 2015. As a result, a total of 166 species belonging to two groups, the zooplankton group has 12 species, 11 genera, 9 families, 3 ordes, 2 classes and the zoobenthos group has 154 species, 120 genera, 59 families, 13 orders, 4 classes. The most richness class is insecta with 141 species, 109 genera, 52 families, 9 orders. Moreover, pH is the environmental parameter that has more effective than others on zoobenthos group both in dry and rainy seasons; whereas, turbidity and total dissolved solids are two factors that effect more strongly than others on zooplankton group. The number of zooplankton species in dry season is lower than in rainy season and in contrast with zoobenthos species. The species of Crustacea and Bivalvia classes are invisible in the dry season, they only appear the species that belong to insecta and Gastropoda classes. Keywords: Aquatic invertebrate, fauna, Song Thanh, Nature Reserve, Vietnam. 1. Introduction divide between Thanh River and Cai River on the East, and Lao PDR on the West. Its forest resources are diverse and abundant. Especially, there were 49 species of plants and 22 species of rare birds, mammals, amphibians, reptiles in Vietnam Red Data Book (2007) and IUCN Red List (2009). It is recorded 301 vertebrate fauna which belong to 89 families, 28 orders; including 53 species of mammal, 183 species of bird, 44 species of reptile, 21 species of amphibian and 25 freshwater fish .