Abstract: In order to deeply explore the distribution pattern, activity mode, and key influencing factors of the migrating finless porpoises in Xijiang Oxbow, Anqing City, we conducted an annual investigation covering 4seasons in 2023, comprehensively applying active and passive acoustic techniques. The results of the passive acoustic investigation showed that the activity intensity of finless porpoises in Xijiang Oxbow has significant spatiotemporal characteristics. Regarding different sections, using a fixd underwater high-frequency acoustic event recorder, 127297, 56566, and 58115 pulse trains of Yangtze finless porpoise were recorded in the upper, middle and lower sections of the Xijiang Oxbow by using fixed underwater high-frequency acoustic event recorders, indicating that the activity intensity of Yangtze finless porpoise translocation population was the highest in the upper section, and there was no significant difference between the middle and lower sections (P>0.05). Subdivided into each season, the activity intensity of winter, spring, and autumn was the highest in the upper waters, and the proportion of the pulse train of Yangtze finless porpoise was 55.64%, 58.34%, and 57.15%, respectively. In summer, the lower water area was the highest, accounting for 56.05%. In winter and autumn, the activity intensity in the upper water area was the lowest, and the proportion of pulse train was 17.7% and 18.7%, respectively. In spring and summer, the activity intensity in the middle water area was the lowest, and the proportion of pulse train was 17.6% and 16.47%, respectively. In terms of seasonal activity intensity, 3814 and 2840 pulse trains were recorded in winter and autumn, respectively, compared to 978 and 1099 pulse trains in spring and summer. This suggests that the activity intensity in winter was significantly higher than that in spring, summer, and autumn (P<0.05). The results of active acoustic survey showed that the average density of fish was approximately 598 ind /1000 m³ in autumn and 55 ind /1000 m³ in spring, with significantly higher densities in summer and autumn compared to that in winter and spring (P<0.05). The spatial analysis indicated that there were fish clusters in the upper waters across all seasons. The highest average fish density was observed in the upper waters of winter and spring, while that in the middle waters exhibited the highest density in summer and autumn. The above research demonstrate that the habitat utilization of the ex-situ finless porpoise populations in the Xijiang Oxbow has significant temporal and spatial characteristics. The distribution pattern of fish resources and the width of the water surface are the main factors affecting the difference of habitat utilization of the Yangtze River finless porpoise. The ex-situ populations prefer the upper water with fish clusters every year. This study provides valuable insights into the spatiotemporal distribution characteristics of Yangtze finless porpoise in the relatively closed ex-situ waters, which can provide technical support for the scientific management and habitat restoration of translocated conservation groups. Additionally, it serves as a reference for the subsequent establishment of new ex-situ conservation waters in the future.