Socket　connections　are　widely　used　to　connect　precast　columns　to　the　foundation　and　the　initial　stiffness　of　the　socket　joints　is　of　great　significance　for　seismic　design.　The　connection　efficiency　of　precast　socket　column　has　an　important　influence　on　its　initial　stiffness.　Therefore,　based　on　the　previous　experiment　research　on　socket　column　by　authors＇　team,　a　finite　element　model　(FEM)　of　ultra-high　performance　concrete　(UHPC)-filled　socket　precast　bridge　column-foundation　joints　was　established　and　verified　by　the　local　damages,　failure　mode　and　hysteresis　curves.　The　key　parameters　that　influencing　the　initial　stiffness　of　socket　joints　were　studied　by　nu-merical　analysis,　and　a　simplified　calculation　formula　of　initial　stiffness　was　proposed.　In　addition,　based　on　the　theory　of　elastic　foundation　beam,　an　analysis　model　for　predicting　the　initial　stiffness　of　socket　joints　consid-ering　rotating　stiffness　of　the　connection　was　developed.　The　theoretical　results　are　verified　by　the　proposed　simplified　equations　and　experiments　results　in　the　literature.　The　method　presented　in　this　paper　can　conve-niently　predict　the　initial　stiffness　of　RC　socket　column-foundation　joints　with　reasonable　accuracy.