Abstract: Ag-polyaniline(Ag-PANI) nanocomposites were synthesized via double in-situ process within toluene-water interface accompanying slowly stirring. The structure and morphology of Ag-PANI compo-sites were characterized by Fourier Transform Infrared Spectroscopy(FT-IR), Scanning Electron Mmicroscope(SEM), Transmission Electron Microscopy(TEM), X-Ray Diffraction(XRD) and X-ray Photoelectron Spectroscopy(XPS). The performance of Ag-PANI nanocomposites were characterized through Cyclic Voltammetry (CV), Four-probe method and Thermogravimetric (TG) analysis. Results showed that when the molar ratio of aniline, silver nitrate to ammonium persulfate was 1:0.5:0.1, the nanocompo-site morphology presented uniform fibers of which the diameter was 120 nm. The silver nanoparticles distributed homogeneously within polyaniline and the average diameter was about 10 nm. Compared with pure PANI fibers, Ag-PANI composite showed higher conductivity (13.3 S/cm), decomposition temperature (482 ℃) and electrochemical activity.