NiO-Ag2S nanocomposite is synthesized by hydrothermal method with special photocatalytic. Combined the photocatalytic properties of both lamellarstructure NiO and Ag2S nannoparticles, the space of NiO are filled with Ag2S nannoparticles uniformly. Through the SEM, two-dimension EDX, and XRD analysis, the morphology and uniformity crystallinity of NiO-Ag2S nanocomposites are revealed. As a simulation reaction, the photocatalytic degradation of methyl orange in NiO-Ag2S nanocomposite suspension irradiated by 500 W Xe lamp isinvestigated. As a result, The photocatalytic ability of NiO-Ag2S nanocomposite is higher than NiO2 and Ag2S. And the photocatalytic efficiency is 30% higher than the physical mixture of NiO2 and Ag2S(mass ratio:1:1) after irradiating 180 min. We believe that p-n junction of NiO-Ag2S nanocomposite is the important factor for the high catalytic performance.