Abstract: The effect of silver carp (Hypophthalmichthys molitrix) stocking and fertilization on plankton community of enclosures ecosystem in saline-alkaline ponds were studied.After stocking silver carp in enclosures,the abundance,chlorophyll-a content and primary productivity of phytoplankton increased,and the biomass of phytoplankton was mainly composed by small species,such as diatom and green algae.Moreover,Euglnophyta and Chrysophyta were also sub-dominant species.The biomass of zooplankton decreased with fish stocking,and that of Cladocera was greater in control than in fish-culture enclosures.Zooplankton community was dominated by larger species such as Daphnia carinata in control enclosures.Fertilization,especially applying inorganic fertilizer,significantly increased the abundance and primay productivity of phytoplankton and the biomass of zooplankton.Although the biomass of plankton in the enclosures applied organic fertilizer was greater than that of control enclosures,the primary productivity and chlorophyll-a content of phytoplankton,the diversity index of plankton,and the P/R ratio were very low,and thus,silver carp grew slowly.The effect of filter feeding fish and applying fertilizer on the structure of plankton community was also discussed.