Electrically　conductive　polymer　composites　have　been　widely　used　in　recent　years.　The　resistivity　of　the　composites　is　influenced　by　several　factors.　The　conductive　silicone　rubbers　(CSRs)　were　prepared　by　adding　the　nickel-coated　graphite　(Ni-G)　and/or　nickel-coated　carbon　fiber　(Ni-CF)　into　liquid　silicon　rubbers　which　were　then　subjected　to　the　vulcanization.　The　effect　of　particle　shape　and　size　on　the　electrical　conductivity　of　CSR　was　investigated;　the　results　indicate　that　Ni-CF　filled　CSR　have　lower　percolation　threshold　than　Ni-G　filled　CSR.　Compared　to　the　filled　particles　with　larger　size,　a　higher　amount　of　smaller　particles　are　needed　to　form　the　same　conductive　pathway　in　CSR.　Thus,　there　are　more　contact　points　in　conductive　pathway,　which　increase　the　total　contact　resistance.　The　volume　resistivity　of　CSR　can　be　significantly　reduced　by　the　doping　of　Ni-CF　particles,　while　the　effect　begins　to　wear　off　under　high　doping　content.　The　fiber-like　Ni-CF　has　a　good　bridging　function　for　the　formation　of　conductive　pathway　in　CSR,　which　is　greatly　enhanced　by　increasing　the　length　to　diameter　(l/d)　ratio　of　Ni-CF　particles.　Therefore,　doping　of　the　particles　that　have　low　percolation　threshold　can　reduce　the　resistivity　of　the　composites.　POLYM.　COMPOS.,　36:1371-1377,　2015.　(c)　2014　Society　of　Plastics　Engineers