Abstract: By testing the environmental radionuclides ²¹⁰Pb_ex and¹³⁷Cs in the sediment cores of Nanyi Lake in 2008, 2014 and 2015 supplemented by the mutually confirmed ²¹⁰Pb CRS dating model and ¹³⁷Cs dating time scale method, the sediment accumulation rates (SARs) over the past 100 years were quantitatively estimated. According to remote sensing visual interpretation method, the spatial and temporal variation of lake areas in Nanyi Lake during the period of 1985-2016 were obtained. Combined with the constructed lake sediment transport model, the annual amount of sediment transport fluxes (STFs) via the outflow river of Nanyi Lake was quantitatively estimated. Based on this, the correlation between lake SARs, STFs and lake area change was further analyzed. The results indicated that the distribution characteristics of ²¹⁰Pb_ex and¹³⁷Cs in the sediment core section of the same lake area in different years were similar, and the distribution of ²¹⁰Pb_ex showed the trend of decreasing with increasing depth, while¹³⁷Cs recorded the first sedimentation in 1954 and the maximum peak of sedimentation accumulation in 1963 at the depths of 24 and 16 cm, respectively. SARs of Nanyi Lake showed a fluctuating trend as a whole. High SARs appeared around the 1950s and a slow rising trend was observed since then, which maybe closely related to the dual impacts of natural and anthropogenic influences in different historical periods. Overall, a shrinking trend was found and the area decreased by 57.37 km² over the past 31 years. Spatially, the declined areas were focused on the northwest, northeast and southeast regions of the lake. The excessive reclamation around the lake was the dominant factor influencing the declined lake areas over the past decades. The annual amount of STFs of Nanyi Lake was about 1 904.60 t/a. Both of SARs and STFs were greatly affected by the lake areas, and SARs showed an exponential increase trend but a linear decrease for STFs along with the expanding of lake areas.