The historical changes of river channel (river floods) in the lower reaches of the Yellow River has been holly debated by the historians in China. In Nansihu Lake area, the sedimental environment has undergone great change, since the evolutionary history of the lake was strongly af fee led by floods of yellow River in historical times. High-resolution lacustrine sediments, reflecting the history of lake evolution, could be used Lo decipher the changes of river channel (river floods) in tne Lower Reaches of the Yellow River. Two sedimentary cores (DS₁ and DS₂) are taken by Livingstone in Dushan Lake, one of the sub-lakes of Nansihu Lake, 1996.The analysis of environmental indexes including pigments, TOC, TN and magnetic susceptibility, frequency dependent susceptibility, of lake sediments in the cores of DS is synthesized to indicate the environment changes in Nansihu Lake in the past 3000 years. About 2400aBP a clear environmental change occurred in the catchment of Nansihu Lake. From BC400s to ADI 70's and AD1200s-1870s are two main floods periods on the lower reaches of the Yellow River. Before 2400aBP the lake was not formed in the area which may be a depression in the edge of fluvial fan of the Sihe River and the Chenghe River. After 2400aBP the lake came into being and was enlarged due to the alluvial fan emerging from the overflow of the Yellow River, especially in BC400-AD170 and AD1200-1870.The link-up of the Grand Canal and the requisition for canal transportation from Lo AD1870 accelerated the lake expansion. From 1872, Nanyang Lake, Dushan Lake and Weishan Lake were united into one large lake-Nansihu Lake.