Abstract:  The system of stability of the tidal flats, including standardized analytical methods and standards, has not been built up by now. This paper, uses the radial sand ridges off Jiangsu coast as the study area, and uses the spatial analysis of GIS, the information on low tide waterline from remote sensing images and the occurrence rate of low tide as tools to analyze and make a quantitative classification of stability of tidal flats. The relationship between the occurrence rate of low tide and the stability of the tidal flats is: the higher the occurrence rate is, the more the stability of tidal flats is; the lower the occurrence rate is, the more the instability of tidal flats is. According to the remote sensing information in nearly forty years,the spatial and temp-oral distribution and changes of the coefficient of the stability of coastal beach have been quantitatively determined . It indicates that the area of Dongsha sandbank has the highest stability, followed by Gaoni sandbank and Tiaozini sandbank. Combining the reclamation planning area of 100 million acres of Tiao-Gao-Dong, the stability of the 3 areas of inning of tidal flats was evaluated. It indicates that Dongsha planning is the best, followed by Tiaozini planning and Gaoni planning. Based on the low tide occurrence rate, the stability analysis of the tidal flats could be used to provide a reference to the partition layout optimization for the study, the development and the protection of coastal beach.