The fish community in Jize Reservoir were seasonally investigated from September 2017 to October 2019. The main fish resources were detected by dual-frequency identification sonar (DIDSON), and the fishery acoustic data were processed by Software Echoview. A total of 30 fish species from 7 families 5 orders were collected, with 28 species of freshwater fish, 1 species of estuary fish, 1 species of emigratory fish. And the herbivorous fishes, phytophagous fishes, planktivore fishes, omnivorous fishes, primary carnivorous fishes and second carnivorous fishes were 2,3,2,9,5 and 9 species respectively. The planktivore feeding fishes including silver carp and Bighead Carp ranked No.1 in both individual number and mass in catches. The dominant fishes (IRI>1 000)were Hypophthalmichthys molitrix, Hypophthalmichthys nobilis, Hypophthalmichthys nobilis, Coilia nasus. The total number of fish was 133 300 and the total resource were 115 800 kg respectively in Jinze Reservoir by the DIDSON, the fish stocksperm 2 was at a high level according to water conservancy industry standard of the people's Republic of China SL 563-2011, ICS 93,160, P55. The present fish community structure was significant difference comparing with that before the reservoir was running, but which was high similarity with the fish fauna in Lake Taihu.