By Diels-Alder reaction of polyimide advantage is that the reaction conditions ease, Yield is generally very high, and in the process does not release by-products. Since maleimide double bonds for electron-rich dienes with high activity and easy to get, So bismaleimide in the synthesis of polyimide Diels-Alder reaction is almost double as the sole parents diluent with a variety of both ene reaction to obtain a polyimide. Both ene structure is very diverse, often difficult preparation, which is the biggest obstacle to the Diels-Alder reaction of polyimide. There are available both ethylenically 2- (hydroxymethyl) -1,3-butadiene, and double false fulvene both carbon atoms, such cyclopentadienone, pyrrole, and thiophene-dioxide. When the multi-diene and both parents ene as other substances than can be high relative molecular mass. When BMI excess prepolymer with maleimide end groups can be generated thermosetting polyimide. And furan compound, removing CO2 obtained aromatic polyimide. Utilizing Diels-Alder reaction of polymers are generally thermally unstable at higher temperatures due to the occurrence of the reverse Diels-Alder reaction of depolymerization. As monomers with polyimide ring condensed to obtain a polyimide common requirement, the resulting polymer must be dissolved in the reaction solvent in order to obtain a high molecular weight.