Being advantageous for saving energy, protecting the environment and being economical, the foamed bitumen can be widely used in large sized road repairing projects. However, being meta-stable may make it hard to control and measure the flow of foamed bitumen during the foaming process. In order to achieve a stable flow rate of foamed bitumen, this paper proposes that an indirect method should be adopted to control the flow rate of foamed bitumen. Based on the conical annular gap flow adjustment theory, it converts the traditional bitumen sprayer and designs a new flow control method of bitumen, which has been proved by the bitumen flow control test. It can effectively improve the flow control stability of bitumen. The outlet pressure method is used to control the foaming water flow, which has been verified. The method is able to control the foaming water flow in a stable manner. According to what has been researched, setting up the engineering flow control equation of bitumen and foam may prove that when its fitting degree may be over 0.99 and its probability more than 0.05, the control equation is effective.