Abstract: Under the influence of natural changes and human activities, the location and morphology of beaches are constantly evolving. In order to accurately evaluate the evolution process of beaches and provide a basis for coastal engineering design and the formulation of beach erosion protection strategies, In this study, a large number of satellite images from 1984 to 2021 were used to identify the positions of dry/wet line, waterline on study transect using sub-pixel technology and combining automatic and manual interactive recognition methods, the position of the mean high- and low-tide lines were further obtained, the spatio-temporal evolution of the three typical beaches was investigated. The research results indicate that human activities (including coastal engineering construction) and the topography of beaches (headlands, degree of beach closure) are the main factors affecting beach evolution. Taiping Bay Beach has been in a basic stable state for a long time under the protection of embankments on both sides, with a high tide line evolution rate threshold of 0–0.1 from 1984 to 2013; The sand replenishment activity carried out by Fushan Bay Beach in June 2017 coincides perfectly with the average high tide line of Fushan Bay obtained in this article, which rapidly silted up after 2017 , with an accretion rate as high as 0.6–1.8; In addition, the rise in sea level has also had a certain impact on the evolution of Qingdao Beach, and the average high tide line of Liuqing River Beach has shown a trend of erosion in recent years ,with an erosion rate threshold of 0.6–1.1.