A photosensitive polysiloxaneimide precursor was synthesized from oxydianiline, bis(p-aminophenoxy)dimethylsilane, and a diacid chloride. This diacid chloride was prepared by the reaction of thionyl chloride with a diacid, which resulted from the reaction of pyromellitic dianhydride with hydroxyethylacrylate in N-methylpyrrolidone (NMP). The adhesion properties between polyimide and substrates such as SiO2 wafer were improved with introduction of siloxane moiety into the polyimide chain. The dielectric constant decreased with increasing siloxane moiety content. The photocrosslinking reaction results show that an 88-90% gel fraction was reached under the irradiation of a high-pressure mercury lamp.