Active　tendon,　consisting　of　a　displacement　actuator　and　a　collocated　force　sensor,　was　first　presented　by　Preumont　and　his　co-workers　to　attenuate　the　vibration　of　large　flexible　space　structures,　and　the　control　algorithm　adopted　by　them　was　integral　force　feedback.　This　paper　presents　a　new　proportional-integral　(PI)　force　feedback　algorithm　to　achieve　larger　damping　ratios　for　the　structure　without　the　requirement　of　structure　model.　Stability　of　the　control　system　is　shown,　and　simulations　of　a　structure　similar　to　JPL-MPI　demonstrate　the　effectiveness　of　the　proposed　algorithm　for　vibration　control　of　space　structures.