The priority direction of mine dust control is to suppress dust generation and flying at the source. Foam, a gas-liquid two-phase medium, has some unique advantages of large dust covering area, strong adhesion ability and fast wetting of dust. It is an efficient way of dust suppression, especially for respiratory dust. However, there is limited research on the morphology and properties of dust suppression foam in the past, resulting in a certain blindness in the preparation and utilization of dust suppression foam. And there is a problem of a large amount of spray foam in exchange for higher dust suppression efficiency, which restricts the low-cost application of this technology in mines. Therefore, in this study, a theoretical derivation was combined with experimental research and quantitative analysis to study the process and law of dust suppression foam drain, the micromorphology of dust suppression foam, the performance influence mechanism and the quantitative evaluation method. These results show that the drain factor w is related to the height of the foam column and the liquid of foam in the foaming process. The higher height of the dust suppression foam and the greater liquid content, the value of the discharge factor w will be lower. The predicted value of w and the theoretical discharge curve calculated by the drainage model show a high degree of consistency with the experimental results, which verifies the accuracy of the theoretical model. The results show foam size distribution, average diameter with the concentration of foaming agent changes. At a low concentration (1%), the number of foam decreases and large particle size bubbles increase. The addition of low-concentration (