Dajingshan Reservoir is a middle sized pumped storage reservoir, located in Zhuhai City, Guangdong Province, South China. To understand the community structure of the meta-zooplankton in the special water body, pelagic zooplankton was investigated monthly or biweekly from March to December in 2006. The meta-zooplankton was composed of 32 species rotifers, 4 species cladocerans and 9 species copepods. Rotifers was dominated by Brachionus, such as Brachionus angularis and Brachionus forficula. Bosmina longirostris was the dominant species of cladocera. In copepoda, Limnoithona sisnensis was the most abundant species, followed by Mesocyclops thermcyclopoide. Limnoithona sisnensis is a small sized species, with adult body length from 0.3 mm to 0.5 mm. It can adapt to high salinity, and invade into the Dajingshan Reservoir with water pumped from Xijiang River. The body mass of the meta-zooplankton ranged from 0.01 μg to 81.92 μg, most species were located within the size range from 0.08 μg to 0.32 μg, and dominated by rotifers. Both abundance and biomass of meta-zooplankton were mainly contributed by copepods, the abundant peak was located within the range of body mass from 0.08 μg to 0.16 μg, while biomass peak (46.43 μg/L) was at the size class from 2.56 μg to 5.12 μg. The abundance and biomass of meta-zooplankton ranged from 21.9 to 876 ind./L and from 17.47 to 1089.73 μg/L, respectively. Both were higher in the flood season than in the dry season. Their peaks occurred in May and September, respectively. Comparing with the other water bodies in the same region, the species number of meta-zooplankton was much lower in the Dajingshan Reservoir. The lower species number was related with high salinity and fish predation pressure. Precipitation and pumped water were the most important factors influencing dynamics of meta-zooplankton, and they significantly modified the effect of temperature. In the dry season, the abundance of cladocerans increased largely with the decrease of fish predation.