A series of 3,3’-bismaleimidodiphenylsulphone/allylamine (3,3’-BDS/A) adducts were prepared by reacting 3,3’-BDS with various molar percentages of allylamine (A). The reaction path, revealed by a model compound study of n-phenylmaleimide reacting with allylamine, indicates that the imido ring of 3,3’-BDS was opened by allylamine resulting in the formation of two amido groups. The infrared and mass spectra of curing 3,3’-BDS/A adducts indicate that the allylamino groups cleaved with the recovery of imido ring of 3,3’-BDS and then participated in the cure reactions. The cure reaction paths depend on the amount of allylamino groups in the 3,3’-BDS/A adducts. When it is in a small amount, the cleaved allylamines will accelerate the homopolymerization of 3,3’-BDS through the maleimide double bonds. When allylamino groups are plentiful, the cleaved allylamines might polymerize by themselves through the allyl groups. A decomposition mechanism of 3,3’-BDS/A adducts was suggested by mass spectra.