Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the surface water of the East Lake, China were investigated in winter (2012) and summer (2013). A hundred and eight samples were collected from 36 sampling sites and analyzed for the 31 PCB and 10 PBDE congeners. Concentrations of both PCBs and PBDEs showed obvious seasonal variations. The average PCB concentrations in the East Lake ranged from 3.17 to 6.09 ng L-1 in winter and 0.19 to 0.99 ng L-1 in summer. CB-44, 105, 118 and 179 were dominant in both winter and summer. The average PBDE concentrations in the East Lake ranged from 2.92 to 5.54 ng L-1 in winter and 0.67 to 1.51 ng L-1 in summer. BDE-47 was predominant in both winter and summer, which accounted for more than 37% of the total PBDEs concentration from all sampling sites. Independent-Samples t-test showed statistical significance of RPCBs and RPBDEs between winter and summer samples. The analysis of distribution, pattern and seasonal variations indicatedthe different potential sources of PCBs and PBDEs in the East Lake. The potential eco-toxicologicalrisk was also discussed in the study.