An epoxy composite material containing polyaniline/carbon black and preparation method thereof are disclosed. The epoxy composite material containing polyaniline/carbon black includes a plurality of polyaniline/carbon black composite with core-shell structure distributed in epoxy resin while polyaniline covers on surface of nanoscale carbon black to form the polyaniline/carbon black composite with core-shell structure. The polyaniline/carbon black composite with core-shell structure contains 10˜30 wt. % of nanoscale carbon black. A method for preparing an epoxy composite material containing polyaniline/carbon black includes steps of: adding a plurality of polyaniline/carbon black composites with core-shell structure into epoxy resin; and dispersing the plurality of polyaniline/carbon black composites with core-shell structure in the epoxy resin to produce the epoxy composite material containing polyaniline/carbon black being applied to conductive coating or microwave absorbing elements.