Using a finite volume method based on the Godunov scheme, a two-dimensional saltwater intrusion mathematical model considering the tidal bore effect was established for forecasting chlorinity at water intakes in the Qiantang River Estuary. Based on field data and computational results from the mathematical model, the effects of main factors, including runoff, tides and tidal bore, and riverbed topography, on saltwater intrusion were analyzed. Results show that the riverbed topography affects saltwater intrusion indirectly through changing tides. The larger the river volume is, the larger the tidal range and tidal prism are, leading to intensification of saltwater intrusion. The tidal bore also enhances saltwater intrusion, as chlorinity changes abruptly before and after the tidal bore. Application of the established model in chlorinity prediction shows that the computational results of the model agree with the field data, and the model has significant application value in chlorinity prediction.