The polyamide-amide-imide (PAAI) was synthesized by reacting 4,4'-diaminobenzanilide (DBA) with trimellitic anhydride chloride using a two-stage heating. The precursor of polyamide-acids was formed at first stage and followed by the formation of imide of PAAI. Two polyamide-imides (PAIs) were prepared from benzidine (BZ) or 4,4'-diaminodiphenylether (DPE) with trimellitic anhydride chloride. These three polymers had glass transition temperature in the temperature range of 240-250℃. X-ray data were obtained on thin film specimens cured at 250℃. There was a minimal kind of short-range order consisting of the most probable distances between neighboring chains. The average segmental spacing of short-range order decreased in the order of polymers obtained from 4,4'-diaminobenzanilide (DBA), polyamide-imide, and 4,4'-diaminodiphenylether (DPE). The imidization of three polyamide-imides was confirmed by 15N MAS NMR and FT-IR spectroscopy. 15N NMR spectrum of cured polyamide-imide showed imide 15N peak, thereby providing an evidence for the imidization of three polyamide-imides.