The curing agent for epoxy is synthesized by reacting hexamethylenediamine with acrylonitrile.Synthesis method has been improved.The compositions of the curing agent are analyzed with infrared spectroscopy,mass spectroscopy and nuclear magnetic resonance.It is found that when.the reaction between hexamethylenediamine and acrylonitrile is carried out in the mole ratio of 1: 1,main product of the mono-cyanoethylation hexamethylenediamine and by-product of the bicyanoethylation hexamethylenediamine is produced at same time.