Lakeshore wetlands are an important component of inland wetlands globally, providing ecosystem services such as water purification, maintenance of biodiversity and climate regulation. Delineation of the dynamic borders of wetlands is the basis of wetland research and a key prerequisite for wetland ecosystem conservation, restoration and rehabilitation. Lakeshore wetlands are significantly affected by the dynamic changes of lake water level, characterized by variable range, obvious spatial and temporal differences in the degree and frequency of changes, etc. Moreover, the extent between lakeshore wetlands and lake water bodies is usually difficult to define. Improving the accuracy of lakeshore wetland monitoring is of great significance for the protection and management of lakeshore ecosystems in the context of global change. Massive, Multi-source Remote Sensing Data Provides Reliable Data Source for Accurate Monitoring of Lakeshore Wetlands. Taking Poyang Lake which connect the Yangtze River and is significantly affected by climate change and water conservancy activities as case study area, this study proposes a remote sensing monitoring method for the spatial extent of the lakeshore zone based on the inundation frequency by utilizing dense time-series Sentinel radar and optical data with the support of the GEE platform and OTSU algorithms. We constructed the Poyang Lake dense time series water body and vegetation dataset during 2019-2022. Results show that: the extraction method of lakeshore wetland based on inundation frequency developed in this paper can effectively define the range between lakeshore belt and lake water body, which provides an important methodological reference for monitoring lakeshore zone at a broad scale. The seasonal fluctuation in the water body area of Poyang Lake was remarkable. The receding rate from the peak of summer flood season to the dry water warning level was accelerated year by year from 2019 to 2022, whilst the hydrological cycle of wetland was shortened. The wetland area of lakeshore zone was 3075.83km²,2726.28km²,2953.91km² and 3331.03km² suggesting an overall increasing trend. The growth and development of vegetation in the lakeshore zone were strongly affected by the inundation state. Under the extreme arid climate, the water with inundation frequency of 0-20% showed a non-inhibitory effect on the vegetation, while the area of the region with high frequency of vegetation cover increased significantly. This study helps to deeply understand the spatial and temporal changes of hydrology and vegetation in the lakeshore zone and its dynamic response relationship and could provide a scientific basis for the regulation of lake water level and the protection and restoration of wetlands in the lakeshore zone.