Abstract: The Nanjian coast of Zhuanghe City is one of the typical cape-type muddy coasts in China and has experienced a complex evolution process under the influence of human activities in the watershed and along the coast for nearly a century. Therefore, it is of great significance to study the evolution features of this coast for understanding the evolution of such kind of coast topography. Based on a total of 85 (from 1938 to 2023) years of bathymetric data and remote sensing images, the changes in the scour and silting of tidal flat and underwater topography are analyzed by means of 3S technology. The results show that: ①The area of the Nanjian tidal flat has been decreasing since 1938, being reduced by 85.74% by 2023 and with a total decrease being 49.68 km². And the main factor leading to the shrinkage of the tidal flat is reclamation. ②The underwater topography has been being in a siltation state on the whole, with an average siltation thickness being 0.57m. The evolution law of the scour and silting of the underwater topography is complicated on the scale of decades, tending to show an alternation of scour and silting at different stages and having a poor stability. The isobath lines vary significantly, with the 0m isobath line retreating 0.47 km toward the mainland on the whole, while the 2, 5 and 8 m isobath lines advancing 0.66, 0.99 and 0.16 km toward the sea, respectively.