Circumferential　rod　fastening　rotor　system　is　widely　used　in　heavy-duty　gas　turbines　because　of　its　advantages　such　as　light　weight,　good　cooling,　easy　assembly　and　so　on.　The　force,　torque　or　load　between　components　in　this　type　of　rotor　system　must　be　transmitted　depending　on　the　contact　interfaces.　In　this　paper,　the　normal　and　tangential　interface　contact　stiffness　of　rough　surface　are　obtained　according　to　the　relationship　between　force　and　deformation　of　the　finite　element　contact　model　which　can　reflect　the　surface　topography.　Then,　the　dynamic　analysis　method　is　presented　and　two　models　are　built　to　analyze　the　dynamic　performance　of　composite　rod　fastening　rotor　system.　The　effects　of　interface　contact　stiffness　on　the　natural　frequencies　and　unbalance　responses　of　rotor　system　are　studied.　The　results　illustrate　that　the　normal　contact　stiffness　of　rough　surface　linearly　increase　when　the　normal　load　rise,　but　the　tangential　contact　stiffness　decrease　with　the　tangential　pressure　increasing.　Furthermore,　the　contact　stiffness　has　important　effects　on　the　natural　frequencies　and　unbalance　responses　of　rotor　system.　With　the　growth　of　contact　stiffness,　the　natural　frequencies　increase,　while　the　unbalance　response　amplitudes　of　rotor　system　decrease.