A series of main chain degradable polyimides 6 were prepared by the polyaddition of acetalcontaining diamine monomer 4 with various aromatic tetracarboxylic anhydrides 5, followed by chemical imidization without isolating. The structures of polyimides obtained were confirmed by infrared, 1H nuclear magnetic resonance (NMR) and 13C NMR spectroscopy. Their thermal stability, solubility and transparency have also been investigated. Furthermore, the acid-catalyzed degradation reactions of model compound 7 and polyimide 6d have been studied. These results suggest that polyimides 6 can be recognized as photosensitive polyimides.