Seismic　response　reduction　effect　of　displacement　dependent　friction　(DDF)　damping　on　base　isolated　structure　with　lead　rubber　bearing　(LRB)　is　investigated.　Bouc-Wen　hysteretic　model　and　Coulomb　friction　model　are　adopted　to　simulate　the　mechanical　property　of　LRB　and　DDF　damper　respectively.　Numerical　analysis　shows　that　the　DDF　damping　can　reduce　base　displacement　but　may　increase　the　inter-storey　drift　and　acceleration　response　of　the　superstructure.　On　the　other　hand,　under　the　excitation　of　impulse-type　near　fault　earthquake,　DDF　damping　can　significantly　mitigate　base　displacement.　Meanwhile　the　inter-storey　drift　and　acceleration　response　of　the　superstructure　are　also　more　or　less　reduced.　Besides　parametric　analysis　gives　some　suggestions　on　the　proper　values　of　the　three　main　factors　of　the　friction　damper.