Although　the　two-grid　finite　element　decoupled　scheme　for　mixed　Navier-Stokes/　Darcy　model　in　literatures　has　given　the　numerical　results　of　optimal　convergence　order,　the　theoretical　analysis　only　obtain　the　optimal　error　order　for　the　porous　media　flow　and　a　non-optimal　error　order　for　the　fluid　flow.　In　this　article,　we　give　a　more　rigorous　of　the　error　analysis　for　the　fluid　flow　and　obtain　the　optimal　error　estimates　of　the　velocity　and　the　pressure.