A method for preparing a (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate, wherein, the method comprises: using a 3-carbonyl-bicyclo[2.2.2]octane-2-carboxylate of formular II as a raw material, carring out reductive amination, epimerization and removal of protecting group to obtain the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate of formular I, and the reaction process is shown below, wherein, the R is methyl, ethyl, propyl, butyl, phenyl or benzyl, the X is methyl, ethyl, phenyl or 1-naphthyl, the Y is methyl, ethyl, phenyl or 1-naphthyl, and the X and the Y are not identical, the X group is larger than the Y group; the method comprises: S1, reacting the 3-carbonyl-bicyclo[2.2.2]octane-2-carboxylate with the chiral amine of formula in the presence of an acid to give the 3-amino-bicyclo[2.2.2]octene-2-carboxylate, the acid is a strong organic acid; S2, carrying out reduction with a reducing agent or metal-catalyzed hydrogenation of the 3-amino-bicyclo[2.2.2]octene-2-carboxylate to give the (2R,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate; S3, under strong base conditions, carrying out the ester configuration flip of the (2R,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate to give the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate, the strong base comprises at least one selected from the group consisting of sodium tert-butoxide, sodium tert-amylate, lithium diisopropylamide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide and potassium bis(trimethylsilyl)amide; and S4, carrying out hydrogenation of the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate of formula VI to remove the protecting group to give the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate of formula I. the R is methyl, ethyl, propyl, butyl, phenyl or benzyl, the X is methyl, ethyl, phenyl or 1-naphthyl, the Y is methyl, ethyl, phenyl or 1-naphthyl, and the X and the Y are not identical, the X group is larger than the Y group; the method comprises: S1, reacting the 3-carbonyl-bicyclo[2.2.2]octane-2-carboxylate with the chiral amine of formula in the presence of an acid to give the 3-amino-bicyclo[2.2.2]octene-2-carboxylate, the acid is a strong organic acid; S2, carrying out reduction with a reducing agent or metal-catalyzed hydrogenation of the 3-amino-bicyclo[2.2.2]octene-2-carboxylate to give the (2R,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate; S3, under strong base conditions, carrying out the ester configuration flip of the (2R,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate to give the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate, the strong base comprises at least one selected from the group consisting of sodium tert-butoxide, sodium tert-amylate, lithium diisopropylamide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide and potassium bis(trimethylsilyl)amide; and S4, carrying out hydrogenation of the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate of formula VI to remove the protecting group to give the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate of formula I. S1, reacting the 3-carbonyl-bicyclo[2.2.2]octane-2-carboxylate with the chiral amine of formula in the presence of an acid to give the 3-amino-bicyclo[2.2.2]octene-2-carboxylate, the acid is a strong organic acid; S2, carrying out reduction with a reducing agent or metal-catalyzed hydrogenation of the 3-amino-bicyclo[2.2.2]octene-2-carboxylate to give the (2R,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate; S3, under strong base conditions, carrying out the ester configuration flip of the (2R,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate to give the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate, the strong base comprises at least one selected from the group consisting of sodium tert-butoxide, sodium tert-amylate, lithium diisopropylamide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide and potassium bis(trimethylsilyl)amide; and S4, carrying out hydrogenation of the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate of formula VI to remove the protecting group to give the (2S,3S)-3-amino-bicyclo[2.2.2]octane-2-carboxylate of formula I.