Abstract: A coupled 1 D-2D numerical model for simultaneous hydrodynamic simulation of river-lake systems is presented.The Water Stage Prediction-Correction(WSPC)method,which is originally proposed to treat the inter-reach coupling at junctions in river-network hydrodynamic calculation,is adopted herein to treat the inter-model connection conditions between 1D and 2D models at the coupled boundaries.Under the WSPC framework,the execution processes of 1D and 2D models during each time step are totally independent,implying that we can male use of the existing model at a minimum modification.Compared to traditional decoupling techniques,the WSPC method gives the advantage of fully fulfilled inter-model connection conditions,whose accuracy also may be controlled by tuning the numeric tolerance.The proposed model is verified by hypothetical and practical cases,and the results show its reliability and good prospects in application.