Abstract: The present invention relates to a new aziridine derivative that is represented herein by general chemical formulae (Ia) or (Ib), and to their preparation method. In the said chemical formulae, R2 and R3 can be the same or different, and they are hydrogen, low-quality alkyl or cycloalkyl respectively; R4 can be selected among hydrogen, alkyl, aryl, or amino protective group; and amino protective group is, for example, (Ph)3C, and FMOC(9-fluorenylmethyloxycarbonyl), alkoxycarbonyl, aryloxycarbonyl, aralkyloxycarbonyl and R5CO, R5SO2 where R5 is alkyl, aryl or aralkyl.