The polyaniline (PANI)/CuO nanocomposite particles were synthesized by in situ polymerization, and characterized in structure and morphology. The result indicated that nanometer CuO particles were successfully coated by polyaniline on their surface, and PANI/CuO composite nanoparticles with rod-shaped core-shell structure obtained. Nano CuO had a good catalytic performance and could speed up the decomposition of H2O2, the accumulation of gas volume eventually reached 1500 mL. Conductivity of PANI/CuO nanocomposite particles decreased obviously and the performance on electrical conductivity of composite nanoparticles gradually declined and reduced to 0.02 S/cm, when the content of nano CuO was 0.6 g. PANI/CuO nanocomposite particles had good antibacterial properties, the maximal antibacterial diameters of staphylococcus aureus and Escherichia coli reached up to 35.8 and 19.6 mm.