NOVELTY - One-pot Synthesis of tert-butyl N-aminocarbonyl-3-methyl-L-valine (I), involves: forming reaction solution of tert-butylamine in solvent, cooling to -5 to 5 degrees C, first adding N,N'-carbonyldiimidazole, stirring and reacting for 20-40 minutes till reaction is complete to obtain imidazole-1-carboxylic acid tert-butylamide (II), then adding L-leucine to reaction solution, stirring and reacting for 20-40 minutes till reaction is complete, then adding reaction solution to ice water, concentrating, decompressing, pulping, and filtering to obtain final product comprising compound (I).    USE - For synthesis of tert-butyl N-aminocarbonyl-3-methyl-L-valine (claimed) useful as carbidopa intermediate, where carbidopa is useful as hepatitis C protease inhibitor.    ADVANTAGE - The method for synthesis of tert-butyl N-aminocarbonyl-3-methyl-L-valine uses raw materials that are cheap, has low production cost, is green and environment-friendly process, as does not produce toxic products such as p-tert-butyl isocyanate and trimethyl chlorosilane that can harm to health of operator and thus does not pollute environment, and also does not produce side products i.e. dipeptide and urea; requires simple reaction conditions such as does not need pH adjustment system, and response of time and temperature of reaction condition are simple and easy to operate; has high conversion rate and little by-product formation, and produces product having high yield and purity and good quality.    DETAILED DESCRIPTION - One-pot Synthesis of tert-butyl N-aminocarbonyl-3-methyl-L-valine of formula (I), involves: forming reaction solution of tert-butylamine in solvent, cooling reaction solution to -5 to 5 degrees C, first adding N,N'-carbonyldiimidazole to reaction solution, stirring and reacting for 20-40 minutes till reaction is complete to obtain imidazole-1-carboxylic acid tert-butylamide of formula (II), then adding L-leucine to reaction solution, stirring and reacting for 20-40 minutes till reaction is complete, after reaction is complete adding reaction solution to ice water, concentrating, decompressing, pulping, and filtering to obtain final product comprising compound (I).