Ag coated Ni composite nanopowder was prepared by an electroless plating method. Conductive paste was prepared using the composite nanopowder as conductive phase. The phase structure, morphology, size distribution as well as electrical conductivity of the nanoparticles were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), and resistivity analysis. The results show that the composite nanoparticles possess a core-shell structure with nano Ni as the core and Ag as the shell. The size of the composite nanoparticles ranges from 20 nm to 100 nm. The thickness of Ag layer is about 4 nm. A thick film with resistivity of (1.26~2.83)×10-4 Ω·cm can be obtained by sintering Ag coated Ni composite nanopowder conductive paste at 200 oC for 60 min under 1.33 Pa, and the conductivity of the film is superior to that of the Ni nanopowder, Cu nanopowder and Ag-Cu nanopowder conductive paste.