To　learn　the　flexural　behavior　of　strengthening　ancient　building　timber　beams　extended　by　a　dovetail　joint　with　near-surface　mounted　CFRP　sheets,　the　bending　static　tests　on　22　specimens　were　carried　out,　the　influence　of　dovetail　joints　on　different　location　(pure　bending　section,　shear　bending　section)　and　mortise　and　joints　with　different　connection　modes　(wooden　dowel,　steel　pin　and　no　pin)　on　its　bending　mechanical　properties　is　discussed.　The　test　results　show　that　without　reinforcement　of　spliced　girder　flexural　capacity　is　relatively　low,　only　18.9　%　to　44.5　%　of　the　intact　beams;　improve　flexural　mechanical　properties　of　spliced　girder　strengthened　by　CFRP　sheets,　the　flexural　bearing　capacity　of　intact　beams　85.8　%　to　103.8　%,　the　flexural　rigidity　can　reach　89.86　%　to　134.78　%　of　the　intact　beams.　Stitching　plus　steel　pin　specimens,　the　reinforcement　effect　is　better　than　that　of　wooden　dowels　specimens　and　the　specimens　without　pins.　The　reinforced　beams　of　the　dovetail　joints　in　the　shear　bending　section　basically　conform　to　the　assumption　of　the　flat　section,　but　the　reinforced　beams　of　the　dovetail　joints　in　the　pure　bending　section　do　not　conform　to　the　assumption　of　the　flat　section.　©　2018　Indian　Pulp　and　Paper　Technical　Association.　All　rights　reserved.