We study ZnO-NiO mixed crystal thin film as a wide band p-type material for the hetero-junction with ZnO. As for the hetero-junction of the ZnO ( n-type ) and the NiO which have relatively stable p-type semiconductor characteristics, there are issues on the crystallographic mismatch and the band offset of the valence band as well as the conduction band . We made the ZnO-NiO mixed crystal thin film in all composition range with the substrate temperature of 250°C, using magnetron sputtering process and acquired the basic data for the change of electrical conductivity with conduction type. In addition, a high-quality thin film was made by using a Pulse Laser Deposition ( PLD ) , and the band diagram of the ZnO-NiO mixed crystal system was illustrated from the analyses of XPS, NEXAFS and optical absorption measurements. As a result, the offset of ZnO-NiO mixed crystal film is proportionally decreasing with increasing the content of ZnO in NiO film. And the characteristics of the diode with the hetero-junction of ZnNiO/ZnO were improved compared with that of NiO/ZnO. The reasons were discussed with the data of the band offset, the crystalline of the films and the interface properties with the NiO/ZnO and the ZnNiO/ZnO.