The objective of research was to determine the diversity of zoobenthos and baseline document supply to build bioassessment program in Hau river. The study was conducted at 9 sites of sampling consisted of 4 sites in the Hau river and 5 sites in its tributaries with two sampling times (12/2013 and 03/2014) in dry season period at Hau Giang and Soc Trang province. The results showed that there were 55 species of benthic macroinvertebrate belonging of 7 classes: oligochaeta, polychaeta, gastropoda, bivalvia, crustacea, hirudinea and insecta. Among them, the species number of gastropoda and bivalvia classes was higher than that of others with 28 species (51%) and 9 species (16%), respectively. The composition of zoobenthos in the first times (28 species) was lower than that in the second times (48 species). The different of zoobenthos species between Hau river and its tributaries was not found. Gastropoda class was the most abundance group and ranging from 15-19 species. The mean of zoobenthos density on Hau river (395±503 ind.m^-2) was higher than that on its tributaries (163±100 ind.m^-2). Common species in study area was Branchiura sowerbyi, Limnodrilus hoffmoisteri (oligochaeta), Assiminea sp., Clea helena (gastropoda), Corbicula fluminea (bivalvia). The Sorencen?s similarity index between Hau river and its tributaries is 0.5. The Shannon?Weiner diversity index was low and varying from 0.82?2.57. Mean diversity index on its tributaries (1.83±0.46) was higher than that on major river (1.50±0.44). In general, benthic macroinvertebrate was quite diversity and they could be indicator organisms to appreciate organic pollution of research area.