Oxide semiconductors, including binary and ternary oxides, are promising to be utilized as active layers in electronics. The heterojunctions based on oxides exhibit many attractive physical and structural properties and are preferably used to fabricate devices. Herein, Sr 3 Al 2 O 6 /Ga 2 O 3 heterojunction is fabricated using radiofrequency magnetron sputtering on silicon substrate, which shows an enhanced current-voltage characteristic under the 254 nm ultraviolet light illumination due to the photogenerated carriers in Ga 2 O 3 . In addition, the heterojunction provides evident rectified properties in the dark, and the improved rectified properties can be obtained under the 254 nm UV light illumination due to the electron-hole pairs separation in the depletion region due to the built-in electric field, while the rectified ratio decrease from %700 at AE0.5 to %20 V at AE5 V, which is due to the electron tunneling caused by shrinking depletion layer. Moreover, the band offsets of the heterojunction is determined by the X-ray photoelectron spectroscopy, which suggests a type I alignment with conduction band offset of 0.94 AE 0.02 eV and valence band offset of 0.53 AE 0.02 eV. The interfacial energy band offsets verify the potential implication for their rectifying property.