Studies on association effect of HPMBP and different amine extractants (N1923,DOA, TOA) in benzene and association constents of HPMBP and TOA in different diluents were carried out. The association compounds of TOA and amine extractants exist widely,which were associated through hydrogen bond into 1: 1 compounds. The order of association ability (TOA>DOA>N1923) was consistent to their extraction abilities. Therefore, in different diluents, the association order of HPMBP and TOA was toluene>cyclohexane>n-hexane>benzene.