Intertidal mudflats are productive habitats and monitoring their morphodynamics is critical to the sustainable management of their ecological values. The mudflat in Deep Bay, situated between Hong Kong and Shenzhen (China) and designated as two adjacent Ramsar Sites, serves as an internationally important foraging ground for waterbirds on the East Asian-Australasian Flyway. Compared to traditional ground surveys, satellite remote sensing provides a low-cost and efficient tool to reconstruct intertidal topography.This study leveraged long-term records from Landsat satellites and near-daily observations from PlanetScope satellites to estimate the topography of intertidal mudflats in Deep Bay in multiple periods in 1991–2020 and 2020–2021 respectively. The waterline method was used to delineate contours from the satellite images by combining image thresholds at different tide heights and sea level information from nearby tide gauge records, which were then interpolated to generate intertidal digital elevation models. The estimated topography showed high accuracies when validated with in situ measurements of the mudflat surface.Comparison among periods indicated that both accretion and erosion occurred at different locations with average rates of change from -1.4 to 2.8 cm per year. Sedimentation was evident near the mangal regions which flattened the slope and led to a gradual seaward extension of mudflats at mean sea level, while slope steepening tended to occur at lower levels along the river channels. Such topographic changes, combined with seaward expansions of the intertidal mangal, have caused temporal fluctuations in mudflat areas exposed at different tide heights. The results can be applied to studies on coastal environmental processes and management plans of the two Ramsar Sites. Dense time-series observations from PlanetScope satellites can facilitate more frequent sampling within the tidal cycle and monitoring of intertidal topographic changes in future.