Abstract: 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 (<0.1%), the foam uniformity is poor and the number is less. After increasing the foam concentration to a certain range (0.3%−0.6%), the foam uniformity and quantity are improved. Foam can obtain higher half-life, and its morphology is more difficult to be destroyed. But at a higher foaming agent concentration (>1%), the number of foam decreases and large particle size bubbles increase. The addition of low-concentration (<0.3%) polymer to the foaming agent has no obvious effect on the wetting angle of coal dust, but the contact angle increases when enlarging the concentration of polymer. In terms of foaming performance and foam stability performance, the production efficiency and stability of dust suppression foam can be improved after the addition of 0.1% polymer. Based on the analysis of the whole process from the generation of dust suppression foam to its action on the dust cutting source, the indicators for evaluating the foam performance are proposed, and the quantitative evaluation criteria and four grades of dust suppression foam performance are given.