The invention discloses a foaming system of a filling machine. The system comprises a nozzle, and a water supplying system which is connected to the nozzle, wherein the water supplying system comprises a booster pump and a heater; a low-pressure water inlet and a high-pressure water outlet are formed in the booster pump; the low-pressure water inlet is connected to a low-pressure water supplying pipeline on which at least one filter is arranged; a water supply control valve is arranged at the upstream of the filter on the low-pressure water supply pipeline; the high-pressure water outlet communicates with a water inlet of the heater, and a water outlet of the heater communicates with the nozzle through a connecting water tube; an adjustable pressure-stabilizing valve and a pressure transmitter are arranged on the connecting water tube; a driving port of the adjustable pressure-stabilizing valve communicates with an air control pipeline; an electrical proportional valve is arranged on the air control pipeline; an intelligent control device is connected between the pressure transmitter and the electrical proportional valve. The foaming system can improve the response speed in pressure regulation control, and the pressure reduction can be reduced, so that the difference between the actual pressure and the pressure for a process can be reduced.