Abstract: Cr-TiO₂ films with porous nanostructure were fabricated by simple sol-gel method using a prepared Cr-TiO₂ with the addition of polyethylene glycol 2 000（PEG 2 000） and were used to assemble Cr-TiO₂/P3HT heterojunction photovoltaic devices.The photovoltaic properties of Cr-TiO₂/P3HT heterojunctions and the correlations between the photovoltaic properties of Cr-TiO₂/P3HT and the structure parameters of porous Cr-TiO₂ were studied in details.The results show that not only the porous structure and the spectral transmittance of the Cr-TiO₂ films can be controlled by the amount of PEG 2 000,but also the power conversion efficiency of the Cr-TiO₂/P3HT heterojunction can be well improved by increasing the amount of PEG 2 000 in Cr-TiO₂ sol.The control mechanism of PEG 2 000 on the properties of porous Cr-TiO₂ film and the Cr-TiO₂/P3HT heterojunctions were analyzed.