Polyaniline was synthesized by the chemical synthesis. Polyaniline as dispersion agent, nano silver / polyaniline composite particles was prepared by In-situ Synthesis in DMF solution. Nano Silver / Polyaniline / PMMA composites were prepared by direct dispersion method. The microstructure and characterization of the sample were studied by UV-Vis absorption spectroscopy infrared spectroscopy and XRD. The composite electrical conductivity was measured by four-probe method, showing that nano silver / polyaniline composite particle size was about 31.0 nm. When the doping concentration of nano-silver reached 0.12%, the electrical conductivity of silver / polyaniline / PMMA composite comparing to the pure PMMA material increased four orders of magnitude.