The flow of the arch structure with a bucket aerator was calculated by the turbulence model, and the results were verified by experimental data. It shows that this numerical model can to a certain extent accurately simulate the jet overflow and cavity behind the bucket aerator. The location of the bucket aerator was studied in the experiment. The laying position of the bucket aerator is better downstream than upstream with the same configuration and hydraulic condition, of which the former has more stable flow, weaker spray and better aeration, so it can successfully alleviate cavitations by air entrainment. This model and the location optimization conclusion for a bucket aerator are of great significance for the configuration and laying of the aerator on arch structure.