Abstract: Flood hazard is one of the factors which can reflect the degree of flood disasters. Assessment and grade classification of flood hazard will provide important reference for flood risk management, emergency evaluation and land use planning, etc. In this paper, the concept of flood hazard in different countries, research process of flood hazard assessment and grade classification, as well as indexes for assessment and grade classification methods on people and region are summarized. The flood hazard assessment index on people mainly incudes flood hazard rating, curve consisting of water depth and flow velocity, as well as multi-indexes combined by flood inundation depth, duration and kinetic energy. As to regions, matrix formed by flood intensity characteristics value and flood return period is the common grade classification method. On this basis,the probable direction of further research in future and some enlightenments on physical experiment study, regulation and standard establishment, as well as its application are put forward.