In order to control the quality of dexmethylphenidate hydrochloride(1),possible impurities were traced and synthesized,including four impurities of 1,namely(±)-threo-2-phenyl-2-(piperidin-2-yl)acetic acid(impurity A),(±)-erythro-methyl-2-phenyl-2-(piperidin-2-yl)acetate(impurity B),(±)-threo-ethyl-2-phenyl-2-(piperidin-2-yl)acetate(impurity E),dimethyl 2,2'-(piperidine-1,2-diyl)bis(2-phenylacetate)(impurity G),and two intermediate impurities,namely(E)-4-methyl-N'-[2-oxo-1-phenyl-2-(piperidin-1-yl)ethylidene]benzenesulfonohydrazide(impurity α)and 2,2'-(hydrazine-1,2-diylidene)bis[2-phenyl-1-(piperidin-1-yl)ethan-1-one](impurity β).The structures of above six impurities were confiirmed by 1H NMR,13C NMR and MS,which could be used as reference substances for the quality control of 1,and provided references for isolation and purification of 1.