The invention provides a method for preparing N-protected and N-unprotected 1-substituted taurine. According to the method, N-allylphthalimide and xanthate serve as raw materials, free radicals are added to the raw materials to obtain N-protected amino alkyl xanthate, N-protected 1-substituted taurine can be obtained through acid oxidation, and N-unprotected 1-substituted taurine is obtained after protection is removed. Materials are easy to obtain, the course is short, and the reaction yield is high. The method is suitable for synthesizing taurine derivatives containing functional groups on a 1-position substituent group side chain.