A　new　variable　friction　system　is　presented,　in　which　the　friction　surface　is　divided　into　three　areas,　i.e.,　one　middle　area　with　small　friction　coefficient　and　two　side　areas　with　large　friction　coefficient.　While　the　displacement　of　the　system　increases,　slide　block　moves　gradually　from　middle　friction　area　to　side　friction　area.　Thus,　the　friction　force　of　system　increases　with　the　displacement　of　the　system.　This　new　system　can　be　used　in　TMD　to　decrease　the　cost　of　TMD　and　avoid　the　disadvantage　of　invariable　friction　TMD.　Based　on　first　order　harmonic　balance　method,　the　equivalent　damping　ratio　and　frequency　of　SDOF　variable　friction　system　is　deduced.　The　influence　of　system　parameters　on　equivalent　damping　ratio　and　frequency　is　analyzed.　The　frequency　response　characteristic　of　SDOF　variable　friction　system　is　discussed.　The　nonlinear　analysis　program　is　developed　and　the　seismic　control　effectiveness　of　variable　friction　TMD　is　analyzed.　The　analysis　results　demonstrate　that　the　frequency　response　characteristics　of　variable　friction　TMD　are　similar　to　that　of　classically　damped　TMD　and　variable　friction　TMD　can　effectively　reduce　structural　response　under　seismic　waves　with　different　peak　values.