Flood is a natural disaster. However, human activities in many circumstances change flood Be-havior. Activities in the catchment such as land clearing for agriculture may increase the Magnitude of flood, which increases the damage to the properties and life. Denbiya flood plain is one of the most severally flood affected areas in North Ethiopia in tana basin by Megech river. The impact of floods had been increase due to a number of factors, with rising sea levels and in-creased development on flood plain. The high magnitude of water that enters in to Megech River overflows this river. For a number of reasons the most frequent choice should be protection from the flooding by revitalizing the people to the safe ground, but there is also a need for a broader and comprehensive program for managing flood hazard in the study area. Flood protection has been helpful and must continue. Side by side, other preventive tools like effective land use plan-ning, creation of a computerized GIS database for the flood prone areas and a detailed flood risk assessment and mapping are required to minimize the harmful effects of flood hazard. This study accomplished to use analytical hierarch process, Arc GIS 10.1, HEC Geo-RAS 10.1 and HEC-RAS.5.0.7. The flood causative factors developed in the Arc GIS, Analytical hierarch process weighted, and overplayed in the principle of pair wise comparison and Multi criteria evaluation technique in order to arrive at flood hazard, and flood risk map and HEC-RAS model to develop flood inundation map. A catchment of Land use/land cover, soil and drainage factor, annual maximum daily rainfall and temperature (1988-2019) and annual maximum daily gauge in river flow data (1980-2019). Flood frequency analysis was done by using Gumball‟s method return period 2, 10, 50 and 100-and the result were 173.86m3/s, 264.2m3/s, 323.9m3/s, 455.5m3/s and 511.14m3/s to obtain respec-tively. AHP weight overlay analysis and from the flood Inundation analysis resulted to shown that 259.6 km2 areas to high and very high flood hazard and 25.21km2 areas to high and very high flood risk. In general, 48,625 people may be affect by this flood result at Dembiya flood plain areas. The overall study indicates that flood hazard, and risk assessment and flood inundation will be aggra-vated in Denbiya flood plains, which needs flood management strategy, coupled with water resource planning in the region to the available risk areas. Finally, for further study it need to consider detail flood damage cost analysis and mitigation measurement.