To assess fish distribution characteristics in Lake Bosten at different seasons and spatial scales as well as the status of fish resources, we conducted lake-wide cruise surveys using a split-beam echosounder (Simrad EY60, 120 kHz) from April to October in 2019. We quantified the spatial and temporal variations in fish density, size composition, and horizontal and vertical distribution. The results showed that fish densities in Lake Bosten in spring, summer, and autumn were 709±141, 8783±2611, and 743±499 ind/hm² , respectively, with mean target strengths (TS) of −52.95, −59.91, and −57.73 dB, respectively. In the horizontal dimension, fish distributed in both the littoral zone and open water area in spring and autumn, and more frequently in the littoral zone and macrophytic area in summer. In the vertical dimension, fish densities decreased with water depth below 3 m in spring, summer, and autumn. The target intensity showed a trend toward increasing with water depth in both the spring and autumn. In summer, the target intensity gradually increased with water depth between 3 and 12 m, while it decreased at water depth greater than 12 m. It is assumed that the spatial and temporal distribution of fish in Lake Bosten is related to factors such as reproduction, growth, and fishing. This study can provide basic data for fish conservation and the rational utilization of fishery resources in Bosten Lake, as well as a scientific basis for lake ecosystem management.