Joint　often　have　a　significant　effect　on　the　dynamical　behavior　of　assembled　mechanical　structures.　The　dynamical　characteristic　of　joint　is　complex,　and　many　researches　focus　on　the　identification　of　it.　A　new　method　to　identify　the　joint　parameters　is　proposed　based　on　the　incomplete　input　information　in　this　paper.　Firstly,　the　unmeasured　frequency　response　functions　(FRFs)　are　identified　by　experimental　and　finite　element　method,　and　completely　FRFs　are　constructed.　Then,　the　dynamic　parameters　of　joint　are　identified　by　iterative　algorithms　based　on　the　completely　FRFs.　The　loss　function　is　established　in　this　paper,　which　can　be　identified　the　parameters　of　joint　by　minimizing　the　loss　function.　Since　this　method　does　not　need　modal　parameters,　it　can　be　used　effectively　to　identify　joint　characteristics　when　the　system　has　heavy　damping　or　closely　coupled　modes.　Furthermore,　the　proposed　method　makes　use　of　only　a　few　FRFs　which　are　not　necessarily　related　to　the　joint　but　related　to　easily　accessible　points.　Thus,　this　method　can　be　applied　to　real　structures　usually　having　rotational　and　inaccessible　degree　of　freedoms.　Finally,　the　validity　and　feasibility　of　the　proposed　method　are　demonstrated　an　example.　The　results　show　that　joint　structural　parameters　can　be　identified　accurately.