Abstract: Coral reef sandbanks are the former landforms of the formation of coral islands. Most of them have no vegetation growth and are easily affected by climatic and hydrodynamic conditions. They are unstable in position and changeable in area and shape. Using the high-resolution remote sensing images from 2005 to 2020, the area and shape changes as well as the movement process of the horizontal position of coral reef sandbanks in the Xisha Islands were analyzed, the stability of the sandbanks was assessed and its influencing factors were discussed. The results show that: (1) Bei Sandbank, Zhong Sandbank, Panshiyu and Kuangzaibei Island are relatively stable, while Xixin Sandbank, Sanzhizai, Quanfu Island and Yinyuzai are yet in an unstable stage. (2) The stability of the coral reef sandbanks come from the integrated effect of sediment supply, marine dynamic environmental conditions and coral reef topography. Under the same monsoon wave and typhoon wave, each sandbank is affected by different hydrodynamic forces due to the different position of each sandbank in the reef flat and the different beach sediment types, resulting in individual evolution process and stable state of eight sandbanks. (3) It is suggested that the wind and salt resistant vegetation (e.g. Casuarina equisetifolia) can be planted on relatively stable Bei Sandbank, Zhong Sandbank, Panshiyu and Kuangzaibei Island, so as to accelerate the development of coral reef sandbanks into coral islands. The monitoring and assessment results of coral reef sandbanks in the Xisha Islands can provide data support for the study on the development of coral reef sandbanks in the South China Sea and the construction and protection management of islands and reefs in the Xisha Islands.