Abstract: The use of N,N-di-2-methylheptyl acetamide (DMHAA),N,N-di-butylbutylamide(DBBA) and N,N-di-butylheptylamide (DBHA) as extractants for the extraction of nitric acid,U(Ⅵ) and Pu(Ⅳ) from the nitric acid solution has been investigated. The molar ratios of DBHA-HNO3 and DBHA-UO2(NO3)2 complexes are found to be 1:1 and 2 : 1 respectively. The complexes of both nitric acid and uranyl nitrate with these amides are highly soluble in aromatic diluent such as toluene without any formation of the third phase. The results show that, by modifying the length of the substitute chain and the degree of branch chain,some substituted amides might be found with which U(Ⅵ) and Pu(Ⅳ) could be coextracted at moderate nitric acid solution and Pu(Ⅳ) could be preferably stripped at low acidity,and the separation of U(Ⅵ) and Pu(Ⅳ) could be accomplished without reductant of U(Ⅵ) and Pu(Ⅳ) in amide extraction.