The invention discloses an extraction method of falcate dolichos root or leaf glucoside A. The method comprises the following steps: (1) taking falcate dolichos root or leaf herbs, adding alcohol aqueous solution for reflux extraction, wherein the weight of the alcohol aqueous solution is 6-12 times of that of falcate dolichos root or leaf herbs; (2) recovering the falcate dolichos root or leaf extract solution obtained from the step 1 under reduced pressure to alcohol till no alcohol taste exists, and adding water or alcohol to liquid medicine; (3) adding hydrochloric acid into the liquid medicine obtained from the step 2 till the pH value is 1-6, and adding sodium chloride into the liquid medicine till the salt concentration to 0.1-2mol / L; (4) placing the liquid medicine obtained from the step (3) on a macroporous adsorption resin column for separation; (5) cleaning and purifying with alcohol aqueous solution, of which the volume is 4-10 times of the column volume of the macroporous adsorption resin column, eluting with alcohol aqueous solution, of which the volume is 4-10 times of the column volume of the macroporous adsorption resin column, collecting the eluant, and drying to obtain falcate dolichos root or leaf glucoside A. The invention further discloses an extraction method of total saponins of falcate dolichos root or leaf, and the application of the falcate dolichos root or leaf glucoside A, the total saponins of falcate dolichos root or leaf, falcate dolichos root or leaf glucoside A hydrolysate and salt thereof and falcate dolichos root or leaf glucoside A derivate in preparing immune-inflammation resistant drugs.