A　doubly-fed　induction　generator　(DFIG)　based　method　for　improving　the　inter-area　oscillation　damping　by　using　fast　active　power　modulation　is　proposed　in　this　paper.　Firstly,　the　detailed　model　of　DFIGs　is　introduced.　Then　the　design　flowchart　of　the　DFIG　damping　controller　is　presented　by　analogy　to　the　power　system　stabilizer　(PSS).　The　method　of　small　signal　stability　analysis　to　the　power　system　is　given.　Though　those　methods,　the　damping　effectiveness　of　the　proposed　controller　is　analyzed　theoretically　by　calculating　the　eigenvalues　of　the　inter-area　oscillation　domain　mode　in　the　4-machine　2-area　system.　The　inter-area　oscillations　in　the　system　with　and　without　the　additional　damping　controller　is　further　compared　though　the　transient　simulation.　Both　the　theoretical　and　simulation　results　show　that　the　addition　of　the　DFIG　damping　controller　can　effectively　improve　the　damping　of　the　system　and　suppress　the　inter-area　oscillation.　©　2019　IEEE.