With the rapid and intensive development of high-tech industrial development zones, they become more sensitive to environmental factors, especially extreme climate events. Under the dual influences of global warming and urbanisation, extreme rainfall events occur frequently in cities, and urban inland inundation poses a significant threat to development zones. Using digital elevation model data, land use data, remote sensing image data, POI data, and measured precipitation data, a one-dimensional and two-dimensional hydrodynamic-pipe network coupling inland inundation model for Jianhu High-tech Zone is constructed. The one-dimensional hydrodynamic layer includes river centre lines, river sections, flow boundaries, and open boundaries, with a total of 68 river sections set up at an average interval of 260 metres. Through grid subdivision, the surface elevation data are assigned to grid nodes to build a gridded two-dimensional terrain model, simulating the evolution of two-dimensional hydrodynamic forces. The grid subdivision is based on research needs, with grid refinement in areas near the river channel and sparse grid in areas away from the river channel to improve model simulation accuracy and efficiency. A total of 8345 triangular grids are divided. After parameter calibration, the model achieves visual numerical simulation of inland inundation conditions. The model is tested using two measured rainfall processes. The model simulation results are consistent with the actual inland inundation conditions. Based on this, the evolution process and distribution characteristics of inland inundation under extreme rainstorm conditions are analysed. Based on the constructed urban inland inundation numerical simulation model, the surface water depth and spatial distribution characteristics of inland inundation under five-year, ten-year, twenty-year, thirty-year, fifty-year, and one-hundred-year return periods are simulated, with severe inland inundation, moderate inland inundation, and general inland inundation classified. The distribution map of inland inundation grades is drawn. The results show that under different return periods, the water depth in the high-tech zone mainly distributes between 0.1 and 0.25 metres, accounting for about 50% of the total inland inundation risk area. Under the scenario of a 100-year return period, commercial residential buildings are mostly affected by heavy rainfall, accounting for 38.4% of the affected area. Transportation facilities and public facilities for healthcare are the next, accounting for 28.5% of the affected area. Public facilities for science and education, culture, and companies are less affected, accounting for 14.2% and 19.8% of the affected area respectively. The evaluation results can provide a scientific reference for the construction and flood prevention planning of high-tech zones.