This paper aims to investigate flood risk in the Mashhad urban area and the role of flood channels in controlling floods. To achieve this goal, the AHP method was used in the ArcGIS software. The parameters included distance from the river, slope, density of canals, distance from canals, precipitation, vegetation, road and pathways, elevation classes, drainage density, distance from roads and land use. Then, by developing the required layers of the urban limits, the weight of each layer was determined based on its importance at the time of flooding. After the final weighting, the layers were compared (AHP) using Expert Choice software, and the resulting matrix was transferred to Idrisi software to determine the final coefficient for each layer. Finally, by applying these coefficients through the Weighted Overlay tab in ArcGIS software, the flood risk zoning map in Mashhad urban area was drawn. According to the results, out of the total area of ​​Mashhad, 6.32 sqm have a very low flood risk, 23.82 sqm have a low risk, 260.06 sqm have a medium risk, 41.88 sqm have a high risk and 2.04 sqm have a very high risk. About 1% of the entire urban area has a very low risk, 7% has a low risk, about 77% of has a medium risk, 12% has a high risk and 3% has a very high risk. The results suggest that 0 to 3-degree slopes, which chiefly have urban application, provide suitable grounds for exploitation. Therefore, the areas particularly relevant to exploitation are those with proper conditions in terms of slope and vegetation. In light of the role of flood channels in flood control, it was found that the floor risk is lower in areas with higher canal density.