Seepage prevention of structural joints in hydraulic structures such as ship locks is a crucial issue related to the safe operation of structures.Surface water-stopping with polyurea coating has emerged as one of the effective methods for seepage control of structural joints in recent years.Focusing on the water-stopping protection system of flat-covering polyurea coating for structural joints,we investigate the deformation of the surface polyurea water-stopping and the bonding performance between polyurea and concrete through opening deformation tests of structural joint specimens,and analyze the failure modes of the specimens,load-deformation behavior,strain distribution law,and interfacial bonding characteristics in detail.The results show that all specimens show tensile failure of the polyurea coating without interfacial cracking or debonding phenomena.Relative humidity and bond length have little effect on the deformation and peak bond stress of the surface polyurea water stop,while the deformation and peak bonding stress increase correspondingly with the increase of polyurea thickness.The deformation of the polyurea coating in the bonding area is mainly concentrated within the range of 40 mm at the loading end,and a bonding length of 50-100 mm can ensure reliable interfacial bonding.