A process for the preparation of R-beta-amino-phenylbutyric acid derivatives of formula, wherein Ar is unsubstituted phenyl or phenyl substituted with one to five substituents selected from the group consisting of fluorine, methyl, trifluoromethyl and trifluoromethoxy; R 1 is hydrogen or C 1-6 alkyl; and R 2 is hydrogen or an amino-protecting group including alkoxycarbonyl and acyl, wherein the alkoxycarbonyl is selected from the group consisting of methoxyl carbonyl, ethoxyl carbonyl and tert-butoxyl carbonyl, the acyl is selected from the group consisting of formacyl, acetyl, chloracetyl, trichloracetyl, benzoyl and phenyl acyl; and wherein the process comprises the following steps: reacting ammonium formate with unsubstituted or substituted phenyl ethyl acetoacetate to obtain an imine, and then reacting the imine with a reducing agent to obtain a racemate of beta-amino-phenylbutyric acid ester; reacting the racemate of beta-amino-phenylbutyric acid ester and a resolving agent to form a salt in an alcoholic solvent or an alcohol aqueous solution, and crystallizing the salt; and hydrolyzing the salt formed from R-beta-amino-phenylbutyric acid ester and the resolving agent, or protecting the amine group to obtain R-beta-amino-phenylbutyric acid derivatives of formula, wherein the resolving agent used in the step is chiral diacylated tartaric acid comprising dibenzoyl-D-tartaric acid, dibenzoyl-L-tartaric acid, di-p-toluoyl-D-tartaric acid or di-p-toluoyl-L-tartaric acid.. wherein Ar is unsubstituted phenyl or phenyl substituted with one to five substituents selected from the group consisting of fluorine, methyl, trifluoromethyl and trifluoromethoxy; R 1 is hydrogen or C 1-6 alkyl; and R 2 is hydrogen or an amino-protecting group including alkoxycarbonyl and acyl, wherein the alkoxycarbonyl is selected from the group consisting of methoxyl carbonyl, ethoxyl carbonyl and tert-butoxyl carbonyl, the acyl is selected from the group consisting of formacyl, acetyl, chloracetyl, trichloracetyl, benzoyl and phenyl acyl; and wherein the process comprises the following steps: reacting ammonium formate with unsubstituted or substituted phenyl ethyl acetoacetate to obtain an imine, and then reacting the imine with a reducing agent to obtain a racemate of beta-amino-phenylbutyric acid ester; reacting the racemate of beta-amino-phenylbutyric acid ester and a resolving agent to form a salt in an alcoholic solvent or an alcohol aqueous solution, and crystallizing the salt; and hydrolyzing the salt formed from R-beta-amino-phenylbutyric acid ester and the resolving agent, or protecting the amine group to obtain R-beta-amino-phenylbutyric acid derivatives of formula, reacting ammonium formate with unsubstituted or substituted phenyl ethyl acetoacetate to obtain an imine, and then reacting the imine with a reducing agent to obtain a racemate of beta-amino-phenylbutyric acid ester; reacting the racemate of beta-amino-phenylbutyric acid ester and a resolving agent to form a salt in an alcoholic solvent or an alcohol aqueous solution, and crystallizing the salt; and hydrolyzing the salt formed from R-beta-amino-phenylbutyric acid ester and the resolving agent, or protecting the amine group to obtain R-beta-amino-phenylbutyric acid derivatives of formula, wherein the resolving agent used in the step is chiral diacylated tartaric acid comprising dibenzoyl-D-tartaric acid, dibenzoyl-L-tartaric acid, di-p-toluoyl-D-tartaric acid or di-p-toluoyl-L-tartaric acid..