Objective The distribution patterns of favorable sand bodies in deltaic sedimentary systems serve as the theoretical foundation for oil and gas exploration. Traditional lobe classification and microfacies analysis methods have limitations in revealing the evolution mechanisms of the channel-lobe system， thus restricting the development of studies on lobe morphology and sand body connectivity. Methods Using the Cretaceous delta of the eastern depression of the Doseo Basin as a model， a flume experiment with a movable base was conducted. By capturing Hi-Res time-series images and sand body morphology data， and applying a new lobe classification method， an effective regional sedimentary model was established. Results （1） A consistent overlapping relationship exists between channels and lobes， where the migration， evolution， or disappearance of channels leads to the formation of new lobes. （2） Within the channel-lobe system， three main evolution mechanisms are driven by hydrodynamic strength： erosion of existing lobes， formation of lobes dominated by sandy deposition， and formation of mud layers dominated by fine-grained deposition. （3） The characteristics of channels determine the type of lobe development， whereas lobe morphology is influenced by factors such as sedimentary slope， tectonic activity， base level， and sediment source conditions. （4） The connectivity of sand bodies is affected by the constituent units of lobes， their contact relationships， lobe properties， and the types of lobe complexes. Later channel evolution can improve sand body connectivity to a certain extent. （5） The eastern depression of the Doseo Basin exhibits two sedimentary models： deep-water and shallow-water delta systems. In the deep-water delta model， the channel evolution area is larger， and connectivity improvements are more pronounced. In contrast， the shallow-water delta model features larger lobe deposition areas and wider planar distribution of lobes. Conclusions The new lobe classification method and the channel-lobe system evolution mechanism are applicable to the study of sand body connectivity and sedimentary models in the study area， and they are expected to be widely used in future delta sedimentary simulation research.