Abstract: Through-out two successive years of 1951-1952, a limnofogical survey of the lake Wu-Li-Hu, really one of the bigger recesses of the lake Tai-Hu, had been undertaken by the Institute of Hydrobiology, Academia Sinica, During the survey, plankton catches were made twice a month. While the majority of the present material dealing with the Clado- cera are based upon such regular catches, others are derived from many occasional collections, especially from the littoral zones. Altogether 30 spe-cies and one variety belonging to 18 genera, 6 families have been recorded These are listed as follows: Family SIDIDAE. Sida crystallina (O. F. Muller) Diaphanosoma brachyurum (Lievin) Diaphanosoma sarsi Richard Family DAPHNIIDAE. Daphnia pulex (de Geer) Daphnia longispina O. F. Muller Daphnia carinata King Scapholeberis mucronata (O. F. Muller) Simocephalus vetulus (O. F. Maller) Simocephalus serrulatus (Koch) Simocephalus exspinosus (Koch) Ceriodaphnia rigaudi Richard Ceriodaphnia setosa Matile Moina dubia de Guerne & Richard Moina macrocopa Straus Family BOSMINIDAE. Bosmina longirostris(O. F. Muller) Bosmina longirostris forma brevicornis Hellich Bosmina longirostris var. cornuta (Jurine) Bosmina coregoni Baird Bosmina fatlis Burckhardt Bosminopsis deitersi Richard Family MACROTHRICIDAE. Hyocryptus sordidus (Lievin) Macrothrix rosea (Jurine) Family CHYDORIDAE. Camptocercus rectirostris (Schoedler) Alona affinis (Leydig) Alona rectangula G. O. Sars Alona quadrangularis (O. F. Muller) Alonella excisa (Fischer) Graptoleberis testudinaria (Fischer) Pleuroxus denticulatus Birge Chydorus ovalis Kurz Chydorus sphaericus (O. F. Muller) Family LEPTODORIDAE. Leptodora kindtii (Focke) The Cladoceran fauna of the lake Wu-Li-Hu is chiefly composed of the cosmopolitan species, widely distributed in temperate zones. However, it is worthy of notice that Diaphanosoma sarsi and Ceriodaphnia rigaudi, generally regarded by some authors as two tropical or sub-tropical speci- es, have also been recorded. The occurrence of Leptodora kindtii even in very small fish ponds along the Yangtze Valley is also of particular inte- rest. The dominant species in the lake, through-out the year, are Bosinina longirostris, Diaphanosoma brachyurum, Daphnia longispina and Chydorus sphaericus.