The invention relates to an extractant used for extracting extracellular vesicle in body fluid and an extracting method thereof. The extractant is prepared from inorganic salt and a water-soluble polymer, the inorganic salt is selected from one or more of ammonium sulfate, calcium chloride, sodium chloride, magnesium chloride or sodium citrate, and the water-soluble polymer is selected from one ofpolyethylene glycol PEG, methylcellulose MC and polyethyleneimine PEI. The extracting method comprises the steps that the extractant is mixed with the body fluid to form a to-be-extracted system, andafter salting-out and centrifugation, the extracellular vesicle can be extracted out. The adopted salting-out method for extracting the extracellular vesicle has the three advantages that 1), the yield is high and is about 70%; 2) the operation is quick and convenient, the extracellular vesicle can be extracted out within 30-45 minutes; 3) the method is not limited by the size of a sample and issuitable for extracting of samples with large-sizes.