Hybrid　position　and　force　control　problem　of　grasped　object　of　a　free-floating　space　manipulator　with　closed　kinematic　chain　is　discussed.　The　dynamics　model　of　synthetical　system　is　obtained　based　on　multi-bodies　dynamics　method　and　kinematic　and　dynamic　characteristic　of　free-floating　grasping　systems,　and　the　control　problems　for　the　object　to　track　the　desired　trajectory　in　workspace　and　adjustment　of　interactive　forces　due　to　the　interaction　between　the　object　and　the　end-effectors　are　discussed.　Because　of　the　high　structure　complexity　and　the　parameter　uncertainty　of　such　systems,　the　scheme　of　radial　basis　function　neural　network　compensation　control　with　better　robustness　to　uncertainty　and　disturbance　is　proposed　to　track　the　desired　trajectory　of　the　object,　and　the　corresponded　scheme　of　internal　forces　control　is　proposed　synchronously.　Therefore,　the　object　position　and　internal　forces　can　be　regulated　simultaneously.　The　effect　of　the　controllers　is　testified　by　computer　simulation　and　simulation　results　verify　that　the　proposed　control　scheme　can　eliminate　the　effect　of　uncertain　parameters　on　the　control　system.　©　2011　Journal　of　Mechanical　Engineering.