The invention discloses a foaming agent for a low temperature-resistant soil pressure balance shield, and a preparation method and the application of the foaming agent. The foaming agent is prepared from formulation components in percent by weight: 2 to 4 percent of alpha-olefin sulfonate, 4 to 10 percent of fatty alcohol-polyoxyethylene ether alkyl sulfate, 1 to 2 percent of coco fatty acid diethanol amide, 0.5 to 1 percent of cocamidopropyl betaine, 0.5 to 2 percent of polyethylene glycol, 0.1 to 0.5 percent of glycerol, 0.05 to 0.3 percent of lauryl alcohol, 0.1 to 0.5 percent of sodium chloride, 0.05 to 0.15 percent of 5-chloro-2-methyl-4-isothiazolin-3-one, 0.05 to 0.2 percent of citric acid and the balance of 79.35 to 91.65 percent of water. The foaming agent disclosed by the invention is used for construction under minus 20 DEG C, is particularly suitable for winter construction and is used for improving a soil body of which a construction soil layer is fine sand, medium-coarse sand and/or sandy gravel, the transparency of the foaming agent used for shield construction under a low-temperature condition in winter is ensured, so that a high foaming rate of the foaming agent is ensured, the foam stability is high, and an adverse effect brought to the construction as the foaming agent changes along with the temperature is reduced.