The mechanism of the reaction of N β dydroxyethylethylenediamine (HEDA) on copper under catalysis for the synthesis of piperazine was studied.The structures of reaction mixtures were identified by GC MS.The preliminary study demonstrats that the above reaction is an intermolecular catalytic amination of alcohol and was proved to proceed through dehydrogenation and hydrogenation.Under the reaction conditions HEDA may undertake the bimolecular disproportionation reaction.Furthermore,the similar nucleophilic substitution reactions between starting material and products,between products and products,possibly occur to give the corresponding byproducts.