Mine fire is a serious threat to workers' health and safety production of coal mines. Foam is used as an efficient extinguishment method in underground coal mines. A new design of foam generator was proposed to solve the drawbacks caused by the complicated operation of conventional foam technology. Experimental results show that the intake air pressure of the new foam generator increases with the foam liquid pressure linearly. The foam production quantity and foam expansion ratio reach maximums at the foam liquid flow of 3.5-4.5m(3)/h. The intake air pressure increases sharply with the outlet pressure especially at a larger foam liquid flow. It is essential to keep the foam generator outlet pressure less than a critical value to get an optimal foam production quantity. The new foam generator has the advantages of simple structure, convenient operation and compact size that is very suitable for fire extinguishment in underground coal mines. The foam technology using the new device makes a good foaming effect in the field and ensures the safety operation of dismantling hydraulic supports from the working face, creating significant economic benefits for underground coal mines.