As an emerging solution to address fish passage challenges in high dams, the fish collection and transportation system was first implemented in China in the early 21st century at several high-head hydropower stations. However, limited data have been reported on its effectiveness. The Wudongde Hydropower Station pioneered a tailrace outlet fish collection scheme, constructing a fish collection and transportation system to assist fish migration. Based on fish collection data from the Wudongde fish collection and transportation system from 2021 to 2023, this study analyzed the characteristics of collected fish using Diversity index, Index of relative importance, Fish autecology matrix , and Ward clustering. The results were cross-validated with environmental impact assessment and design requirements to preliminarily evaluate the system’s efficacy. During 2021–2023, the Wudongde fish collection and transportation system collected 95,281 individuals from 52 fish species. Statistical analyses revealed: (1) All 10 main and secondary fish passing objects were collected, with Percocypris pingi exhibiting the largest average size. (2) The collected specimens of Coreius guichenoti, Rhinogobio ventralis, Jinshaia sinensis, Leptobotia elongata, and Schizothoracinae fishes were mainly 4-year-old, 3-year-old, 6-year-old, 4-year-old, and 4-year-old, respectively. (3) Fish diversity indices indicated moderate overall diversity and a relatively simple community structure. (4) Dominant species included Hemiculter leucisculus, Botia superciliaris, and Pseudogyrinocheilus procheilus, collectively accounting for 87.3% of the total catch. (5) At the species level, Sticky and demersal eggs，Settlement were predominant. Lotic type species dominated, but lentic type also comprised a notable proportion. (6) Ward clustering showed distinct seasonal differences, with July and August forming separate clusters due to high collection volumes, while other months grouped into another cluster. Overall, the Wudongde fish collection and transportation system facilitated migration for most fish species in the river section, with no size-selective bias observed. Preliminary assessment suggests that the majority of the main and secondary fish passing objects collected are potential breeding populations that have reached the age of first sexual maturity. Compared with the breeding time proposed in the environmental impact assessment and design stage, the collection month of some fish objects is delayed or advanced, and the change of fish composition is basically in line with the prediction in the design stage. Compared to similar fish passage facilities, the Wudongde fish collection and transportation system demonstrated superior efficacy by utilizing turbine tailwater for fish attraction, effectively mitigating the hydropower station’s barrier effects. Future efforts should optimize system operations, enhance monitoring, and scientifically evaluate its effectiveness to promote connectivity restoration in the lower Jinsha River.