Polymerization of 4,4＇-bismaleimidediphenyl methane and N-phenylmaleimide was conducted in dimethyl formamide, catalyzed by nanocrystalline titania. The monomers and polymers involved were characterized with infrared spectroscopy, H-1-NMR, and C-13-NMR, respectively. The mechanism of the catalyzed polymerization was discussed as well.