We evaluated the community structure of macrozoobenthos in the mid-reaches of the Heilongjiang River between 2010 and 2011. A total of 117 species of macrozoobenthos were collected, belonging to 16 orders and 49 families. Aquatic insects exhibited the highest species diversity, with 79 species (67.52% of the total) belonging to 34 families and 7 orders. The annual average density and biomass of macrozoobenthos was 58.37 ind/m² and 34.62 g/m², respectively. The average density was highest in spring, followed by autumn and summer, whereas the average biomass was highest in autumn and lowest in spring. sites into three groups with different macrozoobenthic communities. The results of our MDA analysis was consistent with those of the cluster analysis. Pielou index, and Simpson index were highest in the spring of 2010 and lowest in the autumn of 2010. The collectors were the most abundant functional feeding group (41 species). We assessed water quality using the biotic index (BI) and family biotic index (FBI), both of which yielded similar outcomes. The water quality in the mid- reaches of the Heilongjiang River was generally good.