In this study, a YBa2Cu3O7-x (YBCO) superconducting film was prepared on Nb:SrTiO3 (NSTO) substrate via a sol-gel method, forming a YBCO/NSTO heterojunction. The YBCO/NSTO heterojunction was irradiated with UV light, and the photovoltaic characteristics of YBCO/NSTO heterojunction were studied within the temperature range 50-300K. The results show that YBCO/NSTO/In has a significant photovoltaic effect with a high open-circuit voltage (V-OC). At 300K, the V-OC of YBCO/NSTO/In was similar to 0.31V (light intensity similar to 10mw/mm(2)). The V-OC of YBCO/NSTO/In increased with the decrease in temperature and reached 0.79V when the temperature decreased to 50K. The V-OC measurement results under different light intensities indicate that the V-OC decreased with the decrease in light intensity. The current density-voltage (J-V) curves were investigated at different temperatures (no light). The YBCO/NSTO/In heterojunction showed clear rectifying features above 200K; with a decrease in temperature, the asymmetry of positive and negative current decreased. When YBCO underwent superconducting transition, because of the opening of YBCO superconducting energy gap, the V-OC and turn-on voltage (V-t) of J-V curves changed suddenly, and the variations in V-OC (when the light intensity is sufficient) and V-t were consistent with the superconducting energy gap of YBCO. With a decrease in the light intensity, the variations in V-OC decreased; for example, the variation was only 2mV when the light intensity decreased to similar to 20%.