The　fabrication　of　bone　scaffolds　with　interconnected　porous　structure,　adequate　mechanical　properties　and　excellent　biocompatibility　presents　a　great　challenge.　Herein,　a　hybrid　nanostructured　chitosan/chondroitin　sulfate/hydroxyapatite　(ChS/CSA/HAP)　in　situ　composite　scaffold　was　prepared　by　in　situ　fabrication　and　freeze-drying　technique.　The　composition　and　morphology　of　scaffold　were　characterized　by　Fourier　transform　infrared　(FT-IR)　spectroscopy,　X-ray　diffraction　(XRD)　and　scanning　electron　microscopy　(SEM).　It　proved　that　the　low　crystallinity　of　HAP　crystals　were　uniformly　distributed　in　ChS/CSA　organic　matrix　and　the　nanostructured　hybrid　scaffold　exhibited　good　mechanical　property.　The　biocompatibility　and　in　vitro　bioactivity　were　detected　by　MTT-assay,　maturation　(alkaline　phosphatase　(ALP)　activity),　Hoechst　33258　and　PI　fluorescence　staining.　In　vitro　tests　indicated　that　the　hybrid　scaffold　not　only　promoted　the　adhesion　and　proliferation　of　osteoblasts,　but　also　improved　the　growth　of　the　osteoblasts.　Therefore,　it　is　promising　for　bone　repair　application　in　bone　tissue　engineering.　©　2016　Elsevier　B.V.