A combination of multi-mesh gillnet and hydroacoustic survey was undertaken in September (Autumn), December(Winter) 2020 and April(Spring), July (Summer) 2021 in Lake Poyang Basin, Jiangxi Province to understand the spatiotemporal distribution patterns of fish resources and its controlling factors in Zhelin Reservoir during early fishing ban period. Generalized additive model (GAM) was used to identify the key factors affecting the dynamics of fish resources. During the survey, a total of 5440 individuals were recorded, including 54 species representing 36 genera, 12 families and 5 orders with the dominant Cyprinidae including Hypophthalmichthys nobilis, Hemiculter leucisculus and Xenocypris davidi for 70.38%. The hydroacoustic survey indicated that fish density (ind./1000 m³) showed significant spatial-temporal heterogeneity, which was significantly higher in spring and summer (10.42±17.57 and 16.34±11.89) than those in autumn and winter (2.74±3.33 and 2.02±5.07), The fish density in the midstream (3.18±4.76) was significantly lower than those in the upstream and downstream (11.20±15.66 and 5.37±9.33). The total deviation explanation rate of GAM model for fish density was 84.6%, in which the latitude and longitude, season, chlorophyll-a concentration and dissolved oxygen had significant effects on fish density, while the effects of water depth and total nitrogen were not significant. Fish resources were mainly distributed in the regions of 29.12°-29.30°N and 115.05°-115.15°E, and the ranges of dissolved oxygen and chlorophyll-a were 9-12 mg/L and 5-15 μg/L, respectively. There was a trend of miniaturization of fish species in Zhelin Reservoir. In order to maintain the ecosystem stability and fish diversity, it is necessary to strengthen research on the mechanisms that affect the structure and spatiotemporal distribution pattern of fish communities in the future.