Necessity of water has caused human residence around the rivers. Therefore, from the past years in order to flood defense, human has tried to minimize flood destructions. Flood zoning for determining a safe and specific region for agriculture activities, the suitable urban and rural regions are important and it can be an effective factor for reducing flood hazards. In this research, for investigating the potential of HEC-RAS and ARC-VIEW software's in flood zoning, the Plasjan river in Zayandehrood watershed was selected. Therefore, after providing the maps with scale of 1:1000 from this region, regarding instruction of flood zoning maps, 55 sections in 7.4 kilometers of river reach were selected. After collecting hydrologic information of the region, Manning roughness coefficient was determined through Chow table and engineering judgment. Finally, by HEC-RAS and ARC-VIEW software's, the required steps were performed and the maps of flood elevation and area for different return periods of 5,10,25,50,100 and 200- year have been provided. The study results show that, this software has a relatively high accuracy in providing flood zoning maps and 5% estimate error of HEC-RAS in simulating water surface also confirms this accuracy. Considering the changes of 20 percent in roughness coefficient on water depth in different return periods indicates that, the parameter has not the significant effects on the water depth and changes in depth are relatively independent from the roughness coefficient. Therefore, using the HEC-RAS, flood zoning maps were prepared with the highest accuracy.