Abstract: With the development degree of river getting higher and higher, the negative accumulating effects are becoming serious. Evolution analysis results can provide basic support for scientific utilization, protection and management of rivers. Taking the Nanjing reach of the Yangtze River as a typical study case, the monthly Landsat remote sensing images from 1984 to 2020 were collected. The normalized difference water index method, the morphological method, and the proper orthogonal decomposition method were used to extract riverbed boundary and sands and their spatio-temporal evolution characteristics. Results show that in the past 40 years, the riverbed boundary of the Nanjing reach of the Yangtze River was shrunk by 6% due to human activities, and the most violent shrinkage, which occurred during 1984-2005, was near the Changjiangcun. For the five major sandbars in the Nanjing reach, Bagua Sandbar, Meizi Sandbar and Xinji Sandbar had little change; the eroding degree of the head of the Xinsheng Sandbar was similar to the deposition degree of its tail; while the Xinqian Sandbar was gradually deposited from the upstream to the downstream with an area increase of 200%, and the initial, medium and last stages of deposition were during 1984-2000, 2000-2005, and 2005-2020, respectively. The first-order modes of riverbed boundary and sandbar series reflect the time averaged morphology, while other high-order modes reflect the erosion and deposition of local areas. Projection coefficient series can well depict the time evolution feature of the spatial evolution modes.