With　the　increase　of　wind　power　penetration　and　the　participation　of　wind　farm　in　frequency　regulation,　it　is　necessary　to　construct　an　accurate　and　efficient　frequency　response　model　of　the　wind　farm　for　coping　with　the　frequency　related　issues.　This　paper　proposes　a　reduced-order　frequency　response　model　for　doubly　fed　induction　generator　(DFIG)-based　wind　farms　that　participate　in　the　system　frequency　regulation.　Firstly,　to　avoid　measurement　error　of　the　wind　speed　in　open-loop　control　mode,　a　frequency　response　model　of　the　DFIG　based　on　closed-loop　feedback　control　mode　is　constructed　by　linearization　method,　which　involves　the　dynamic　properties　of　the　rotating　part　and　the　control　unit　of　the　DFIG.　Then,　based　on　the　single　DFIG　model,　the　reduced-order　frequency　response　model　of　the　wind　farm　is　derived　by　the　balanced　truncation　(BT)　algorithm.　The　reduced-order　model　is　competent　for　the　scenarios　where　the　DFIGs　operate　in　various　states　in　the　wind　farm,　as　well　as　has　a　low　computational　burden.　The　effectiveness　of　the　reduced-order　frequency　response　model　of　the　wind　farm　is　verified　through　comparisons　with　the　simulation　result.　©　2022　IEEE.