Threaded-sleeve　connection　(TSC)　is　a　new　type　of　semi-rigid　connection　for　spatial　grid　structures.　In　this　paper,　bending　behaviour　of　the　TSC　was　analyzed　and　a　mathematical　model　for　prediction　of　moment-rotation　behaviour　was　proposed.　Firstly,　experiments　were　conducted　to　investigate　the　bending　performance　and　damage　form　of　the　TSC.　The　moment-rotation　curves　of　the　specimens　were　obtained　as　well.　Then,　solid　finite　element　model　was　established　through　ANSYS.　Comparing　the　theoretical　analysis　and　experiments,　it　was　observed　that　the　numerical　results　agreed　well　with　the　experimental　data,　which　indicates　the　feasibility　of　the　finite　element　analysis　method.　Finally,　the　calculation　formul　as　of　the　initial　moment　and　the　initial　rotation　of　the　TSC　were　obtained　through　MATLAB　curve　fitting.　The　shape　parameter　n　was　determined.　Based　on　the　Kishi-Chen　power　model,　the　moment-rotation　model　of　the　TSC　was　developed.　Therefore,　it　will　be　possible　to　take　into　account　semi-rigid　analysis　for　a　spatial　grid　structure　with　TSC　easily　and　find　the　more　actual　behaviour　of　the　structure.　Copyright　(c)　2019　by　The　Hong　Kong　Institute　of　Steel　Construction.　All　rights　reserved.