To investigate the distribution dynamics of Yangtze finless porpoises (YFPs) in Poyang Lake and its tributaries during the middle of the fishing ban, we conducted ten surveys at different water levels between 2022 and 2025. The results indicate that the YFP population is primarily concentrated in the Laoye Temple-Zhuxi Estuary-Piaotou and Duchang-Piaoshan-Meixizui waters. The high water level period is scattered and widely distributed in the lake area, with less distribution in the waterway connecting the Yangtze River and tributaries; The low water level period is concentrated in the main channel and increases in the distribution of sand pits, the waterway connecting the Yangtze River, and tributary tails. The tributaries Gan River, Xin River, Rao River, Fu River, and Xiu River all have distribution of YFPs. Stable, year-round populations were observed in the Gan River (Yangzizhou) and Xin River (Xiniuwan). Migration activities of YFPs are related to seasons and water levels. During winter/low water periods, they migrate from the lake area to the tail of tributaries, while during summer/high water periods, they migrate from the tail of tributaries to the lake area. And as the low water level continues, the distance of migration towards the tail of the tributary may increase for search of resources and space. The KDE model results indicate that the 50% KDE distribution of the YFPs is mainly continuous in the central part of the lake area during the high water level period, while it is fragmented in the lake area and tributary tails during the low water level period. The 50% KDE area decreases with declining water levels, exhibiting a significant positive linear correlation (R=0.721, P<0.05). The fishing ban has led to an expanded distribution range for the YFPs in Poyang Lake. However, the habitat area has decreased and become fragmented due to the normalization of low water levels which may be an important risk factor for the population. The research results suggest that the protection of YFPs in Poyang Lake should focus on the protection of core home range and the connectivity of ecological corridors under the background of normalized low water levels.