Abstract: The technology of spray foam inside roadheader transports foam to cutting head using existing internal water spray pipe to suppress dust with dust source covered.But the resistance of pipeline transportation is high because of its curved and fine structure.The traditional metering pump cannot be used in underground coal mine.The venturi adding device cannot reach the required pressure due to the high resistance loss and low exit pressure.Therefore, the study of high outlet pressure water jet suction is significant.Based on the principle of liquid jet pump, foam agent is added using negative pressure.Also the imbibition characteristics under different structure sizes are studied.Its impact on flow field characteristics and pressure loss is ascertained with the preliminary design of structure parameters using numerical simulation.In addition, the reliability of simulation is verified by laboratory experiment.Results indicate that at field conditions, the suction effect is optimal, pressure loss is minimum, and device reliability is high when the nozzle aperture is 3 mm, the distance between nozzle outlet and throat inlet is 2.5 mm, and the throat diameter and length are 5 mm and 30 mm respectively.In this case, the steady foam agent adding can be achieved under the high resistance of pipeline transportation.