New film forming aromatic poly(amide-imide)s containing isoindoloquinazolinedione (IQ) unit in the backbone chain (polymer XIV) have been successfully synthesized by preparing prepolymers of poly(amic acid-carbonamide). followed by subsequent thermal cyclization of the prepolymers. 4,4-Diamino-3-carbamoylbenzanilide (DACB) V has been synthesized by reduction of 3-carbamoyl-4-amino-4-nitrobenzanilide IV. The prepolymers of poly(amic-acid-carbonamide) (polymers VII and VIII) which exhibit viscosities ranging from 1.4 to 1.7 dl/g have been prepared by a condensation polymerization of monomers such as BPDA, ODA, and DACB. Polymer XIV has been obtained by thermal cyclization of the polymers VII and VIII. During the thermal cyclization reaction, imide ring structure was first introduced and then transformed to the structure of IQ unit. The thermal degradation rate of the resultant polymers were influenced by the cleavage of amide bond but the final char yield was comparable to that of poly(BPDA-ODA).