End-functional silicone coupling agent (dodecyl-trimethoxysilane, DTMS in short) was used to modify the PEO/P(VDF-HFP)/SiO₂ nanocomposite polymer electrolyte (CPE in short) and the effects of different amount DTMS modification were studied. The experiments showed the silicone coupling agent with hydrophobic alkyl chains (-C₁₂H₂₅) self-assembled on the SiO₂ nanoparticles, and the formation of the Si-O-Si cross-linked network in the new nanocomposite polymer electrolyte. Proper content of DTMS modified CPE exhibited improved ionic conductivity and the connection with the photoanode and counter electrode. However, too much content of the DTMS modification changed the conformation of the polymer network and deteriorated the ionic movement. Compared with the performance (3.84%) of original DSSC, the DSSC with functional silicone coupling agent self-assembled CPE (DTMS:SiO₂=2:1, mol ratio) exhibited improved Jsc (7.94mAcm^-2), Voc (0.624V) and the optimal efficiency (5.2%) (measured at AM1.5, light intensity of 58.4mWcm^-2). The Voc of the silicone coupling agent modified polymer electrolyte DSSC is improved obviously, which is mainly due to the hydrophobic alkyl chain end groups formed an insulate layer that retarded the electron recombination at the TiO₂ nanoporous photoanode/polymer electrolyte interface. The DTMS:SiO₂=2:1 modified CPE type DSSC exhibited performance of 6.42% at light intensity of 32.1 mWcm^-2 and 4.94% at 99.2 mWcm^-2.