The vertical distribution and vertical migration of dominant crustacean species was studied by sampling water at different depths at the Wenxin Island site(29°38′10.5″N,119°01′54.1″E) in Qiandao Lake in June,September and December of 2004 and March of 2005.The planktonic crustaceans dominantly distributed at the depth of 10-21 meter from the surface.Different seasons had different The distribution depths of planktonic crustaceans varied seasonally and they sampled from deep to shallow in December,September,June and March.The vertical distribution range was greater in spring and summer than that was in autumn and winter.The dominant species of planktonic crustaceans mainly distributed in the upper middlewater depth(10-21 m)though they were found at all the water samples.The ranges of the vertical distribution varied with species and time.An obviously diel vertical migration was detected in species Neutrodiaptanus incongruens,Cyclops vicinus,Schmackeria forbesi,Daphnia hyaline and Bosmina longirostris.The trend of vertical movement in Neodiaptomus schmackeri,Diaphanosoma brachyurum was not identified clearly.Illumination,temperature and diet resource were the principal environmental factors driving the diel vertical migration.