Abstract:　 In this work， we report on the epitaxial growth and superconducting properties of pure and Y2O3-added YBCO films grown on STO-buffered MgO substrates by pulsed-laser deposition. Depositing a narrow Y2O3 sector （its area corresponds to 2.5% of the surface area of the YBCO target） on an YBCO target， we obtained high quality YBCO＋Y2O3 mixed thin films. The Jc value at 77 K for the mixed YBCO＋YSZ thin film was enhanced. The Jc values at 77 K are 2.25 MA/cm2 and 2.62 MA/cm2 （self field） （0.04 MA/cm2 and 0.09 MA/cm2 （B＝5 T， B//c）） for a pure YBCO film and Y2O3 added sample， respectively， even when both films are prepared under the same deposition conditions. Compared to a pure YBCO film， the performance of the Y2O3 doped film in a magnetic field is remarkably high. The pinning properties for the mixed YBCO＋Y2O3 thin film were strongly enhanced， especi!ally at the temperatures lower than 77 K: the maximum global pinning forces FP （B//c） for the Y2O3 doped sample are 7.8 GN/m3 near 2 T at 77 K， 54.5 GN/m3 near 4 T at 65 K， and 189 GN/m3 near 9 T at 40 K. In the Y2O3-added sample， except for the B//ab axes configuration， the angular dependence of Jc showed a plateau， due to the flux pinning by isotropic pinning centres. This is consistent with the cross-sectional TEM observation of Y2O3 nanoislands randomly dispersed inside the YBCO matrix. Studies to further optimize the synthetic parameters （content of Y2O3 and deposition temperature） are currently under way. Forthcoming results， together with the former ones， will be discussed at the conference. We expect that these studies will further enhance the performance of YBCO＋Y2O3 samples.