The invention discloses a rosin-based polyamine conductive epoxy hardener and a preparation method and application thereof. The preparation method includes: enabling dehydroabietic acid which is a disproportionated rosin purification product to react with polyamine, and depressurizing for distilling to remove redundant polyamine to obtain slightly-red transparent liquid rosin-based polyamine; mixing the rosin-based polyamine with a carbonaceous conductive filler to obtain the rosin-based polyamine conductive epoxy hardener. Pi-Pi interaction between rosin-based polyamine and carbonaceous conductive particles like grapheme is utilized creatively to uniformly disperse the carbonaceous conductive particles in rosin-based polyamine, so that sedimentation is avoided; the rosin-based polyamine conductive epoxy hardener prepared by the method has extremely high amine value and conductivity, and can substantially lower percolation threshold value of conductive adhesives when being applied in preparing epoxy resin conductive adhesives.