To develop novel resin transfer molding (RTM) type oligoimides with lower melt viscosity, three series of phenylethynyl terminated thermoset oligoimides derived from the mixture of 1,4-bis(3,4-dicarboxyl phenoxy)benzene dianhydride (4,4′-HQDPA) and 1,4-bis(2,3-dicarboxyl phenoxy)benzene dianhydride (3,3′-HQDPA) with three different aromatic diamines were prepared, the diamines including 4,4’-oxydianiline (4,4′-ODA), 2,2′-bis(trifluoromethyl)benzidine (TFDB) and 2-phenyl-4,4’-diaminodiphenyl ether (p-ODA). Effects of the chemical structures and molecular weights of the oligoimides on their aggregated structures, melt processability as well as the thermal and mechanical properties of the cured films were then systematically investigated. XRD results indicate that ODA series oligoimides and TFDB series oligoimides show crystallinity in various degree. However, the asymmetric p-ODA enables the p-ODA series oligoimides to exhibit amorphous form. It is found that the amorphous oligoimide (o-p-1) with the molecular weight of 750 shows more lower melt viscosity at a low temperature and the melt viscosity can maintain below 1 Pa·s after o-p-1 is isothermally aged for 2 h at any temperature in the range of 200 ℃ to 280 ℃ by rheological measurements. The corresponding cured film also shows very good thermal stability by TGA. It might be more suitable for RTM processes in the future.