This　paper　addresses　the　theory　of　multi-window　subspace　Gabor　frame　with　rational　time-frequency　parameter　products.　With　the　help　of　a　suitable　Zak　transform　matrix,　we　characterize　multi-window　subspace　Gabor　frames,　Riesz　bases,　orthonormal　bases　and　the　uniqueness　of　Gabor　duals　of　type　I　and　type　II.　Using　these　characterizations　we　obtain　a　class　of　multi-window　subspace　Gabor　frames,　Riesz　bases,　orthonormal　bases,　and　at　the　same　time　we　derive　an　explicit　expression　of　their　Gabor　duals　of　type　I　and　type　II.　As　an　application　of　the　above　results,　we　obtain　characterizations　of　multi-window　Gabor　frames,　Riesz　bases　and　orthonormal　bases　for　L-2(R),　and　derive　a　parametric　expression　of　Gabor　duals　for　multi-window　Gabor　frames　in　L-2(R).