In the synthesis of l-phenyl-5-substituted amino-4-pyrazole N-alkyl amide,it was found for the first time that one of the two aromatic amido groups in the moleculeof 1-phenyl-5-benzoyl amino-4-pyrazole N-alkyl amide was reduced selectively by LiAlH_4.new conclusion was drawn after several experiments have been done that ortho-amino(orsubstituted amino)aryl amide or the aryl amide with its ortho substituent which canbe reduced into an amino group(or substituted amino group)can not be reduced by LiAlH_4.It was further rationalized by quantum chemical calculation. In the synthesis of l-phenyl-5-substituted amino-4-pyrazole N-alkyl amide, it was found for the first time that that one of the two aromatic amido groups in the molecule of 1-phenyl-5-benzoyl amino-4- pyrazole N-alkyl amide was reduced selectively by LiAlH_4.new conclusion was drawn after several experiments have been done that ortho-amino (orsubstituted amino) aryl amide or the aryl amide with its ortho-phenyl which canbe reduced to an amino group (or substituted amino group) can not be reduced by LiAlH_4.It was further rationalized by quantum chemical calculation.