Abstract: A new inodified bismalcimide resin,designated LL-45-1,was obtained by hot melting two different kinds of bismaleimide,one is a commerial product,4,4 bismaleimidediphenylmethane,the other is a substituted bisma-leimide,LL-45-1 resin has a low melting point (about 55℃),which is far below the polymerization temperature,though it maintains the heat resistance of polybismaleimide(decomposition temperature>400℃).Hence it is a heat resistant resin of better property.The composite made from LL-45-1 resin exhibits high strength at 250℃ as well as good thermamoisture stability.It shows that LL-45-1 resin is a hopeful matrix resin candidate for high temperature composites.