Abstract: This study focuses on the flood protection areas on both sides of the Puhe River in Xinmin City of Liaoning Province, using the Mike Flood model to couple the Mike11 one-dimensional model and the Mike21 two-dimensional model. Based on the current status of flood control projects in this river section, it simulates the inundation conditions of flood protection areas under different flood control standards and different breach conditions. Combined with the infrastructure conditions of flood protection areas on both sides, a second line of defense is set up, and the flood inundation conditions of protection areas with different flood control standards under the second line of defense are calculated and analyzed. This provides technical support and experience for flood dispatching, flood risk analysis, and defense line layout in this river section and similar river sections.