Abstract: A quarterly survey on benthic macroinvertebrate was conducted at 11 sampling plots in Jianhu Lake in January, April, June and October of 2011. A total of 52 species mainly belonging to Mollusca, Insecta and Annelida were observed. There were significant differences in temporal and spatial distribution of density and biomass of the benthic macroinvertebrate in Jianhu Lake, the temporal density distribution was showed in the order as winter>spring>summer>autumn, while the temporal biomass distribution was ordered as summer>spring>autumn>winter. The annually horizontal distribution of the density at the 11 sampling plots was ranged from 16 ind/m2 to 23840 ind/m2, the highest density was found at Plot A left, and the lowest density was observed at Plot E right. The annually horizontal distribution of the biomass was ranged from 168 g/m2 to 234347g/m2, the highest point of biomass was Plot D, the lowest point of biomass was Plot I.Margalef index throughout the year between 0.10-2.75, the maximum value appears in autumn, the minimum value appeared in summer. Shannon-Wiener index′s variation range was 0.01-1.09, Simpson Biology index was 0.03-0.65, Pielou evenness index was 0.03-1.43. And they had the same peak value and minimum value in the season, the peak value in summer, the minimum value in winter.