Being hard to foam successfully with too many controlled variables in bitumen foaming, the main controlled variables include bitumen heating temperature, oil-water ratios, and water temperature in the bitumen foaming experiment, all of which are the research aspects, with the average velocity and average density as response parameters. With a target of the maximum expansion ratio of foamed bitumen, the experiment adopts the Box-Behnken design method and the least square method to set up a two-stage response model. After the model is tested, showing to have a higher fitting degree and accuracy, a significance analysis of the controlled variables is made in course of the bitumen foaming course. The optimization is designed, and finally the optimization effectiveness is verified by calculating their numerical value. The research shows that: a) what most affects the expansion ratio of foamed bitumen is first the oil-water ratio and then the bitumen temperature; b) the water temperature least affects the expansion ratio of foamed bitumen; c) when being heated to 165.5°C with the oil-water ratio being 2.5% and the water temperature 46.4°C, the foamed bitumen may attain its largest expansion ratio.