High　concrete-face　rockfill　dams　(CFRDs)　with　heights　of　over　100　m　have　been　quickly　developed　in　recent　years.　The　self-weight　of　rockfill　materials　causes　creep　deformation　of　the　dam　body.　However,　the　creep　analysis　method　of　high　CFRDs　in　finite　element　software　is　few,　and　sometimes,　it　can　also　not　reflect　the　long-term　performance　of　high　CFRDs　well.　Therefore,　it　is　necessary　to　carry　out　the　secondary　development　in　finite　element　software.　This　study　developed　a　subroutine　that　can　run　in　Finite　Element　Method　(FEM)　platform　ABAQUS　to　simulate　long-term　creep　deformation　behavior　of　the　rockfill　materials　more　accurately.　Then,　a　displacement　back-analysis　for　parameters,　based　on　the　Xujixia　high　CFRD　project,　is　performed　by　the　neural　network　response　surface　method　(BP-MPGA/MPGA).　Remarkable　agreements　are　observed　between　simulation　and　field　monitoring　results.　The　calibrated　FEM　model　is　used　to　predict　stress　and　deformation　behavior　of　the　Xujixia　high　CFRD　after　three　years　of　operation　period.　The　result　indicates　that　rockfill　creep　deformation　has　a　significant　impact　on　stress　and　deformation　of　the　high　CFRD　during　the　operation.　This　research　may　predict　long-term　performance　using　FEM　in　the　design　stage　for　high　CFRDs.