The light-emitting diodes （LEDs） was fabricated， which consisted of p-NiO/MQWs/n-GaN heterostructure with NiO as a hole injection layer on MQWs/n-GaN by using Rf magnetron sputtering equipment. The structure， morphology and optical properties of the NiO layer were tested by X-ray diffraction （XRD）， Atomic Force Microscope （AFM） and Ultraviolet Spectrophotometer （UV-2700）， and the results showed that the NiO film had good crystalline quality. The Current-Voltage （I-V） and electroluminescent （EL） characteristics of p-NiO/MQWs/n-GaN heterojunction devices were tested. The I-V characteristic test results showed that the device had obvious rectifier characteristics and the turn-on voltage was about 2.9 V. The test results of EL characteristics showed that the blue-violet light emission was realized at room temperature， and the electroluminescence mechanism of the device was studied by combining the photoluminescence （PL） spectrum of MQWs/GaN and the energy band structure diagram of the device.