In　this　paper,　the　kinematics　and　dynamics　of　free-floating　space　robot　system　with　dual-arms　are　analyzed.　It　is　shown　that　the　dynamic　equations　of　the　system　are　nonlinearly　according　to　inertial　parameters.　In　order　to　overcome　these　problems,　the　system　is　modeled　as　under-actuated　robot　system,　and　the　idea　of　augmentation　approach　is　adopted.　It　is　demonstrated　that　the　dynamic　equations　of　the　system　can　be　linearly　depending　on　a　group　of　inertial　parameters.　Based　on　this　result,　a　robust　variable　structure　control　scheme　for　freefloating　space　robot　system　with　dual-arms　with　uncertain　inertial　parameters　to　track　the　desired　trajectories　in　joint　space　is　proposed,　and　a　planar　space　robot　system　with　dualarms　is　simulated　to　verify　the　proposed　control　scheme.　The　advantage　of　the　control　scheme　proposed　is　that　it　requires　neither　measuring　the　position,　velocity　and　acceleration　of　the　floating　base　with　respect　to　the　orbit　nor　controlling　the　position　and　attitude　angle　of　the　floating　base.　In　addition　to　this　advantage,　it　is　computationally　simple,　because　of　choosing　the　controller　robust　for　the　uncertain　inertial　parameters　rather　than　explicitly　estimating　them　online.　Copyright　©　2009　by　ASME.