To　prepare　ChS/CSA/nHAP　in　situ　composite　scaffold,　and　evaluate　its　cytocompatibility,　ChS/CSA/nHAP　composite　scaffolds　were　prepared　through　in　situ　fabrication　and　freezing-drying　technique.　The　rat　osteoblasts　were　isolated　and　cultured,　which　were　used　to　set　up　in　vitro　evaluation　model.　The　effect　of　ChS/CSA/nHAP　in　situ　composite　scaffolds　leach　on　the　relative　proliferation　rate　of　rat　osteoblasts　were　detected　by　MTI-assay,　the　content　of　osteoblasts　protein　were　determinated　by　BCA　method　and　the　content　of　ALP　were　also　tested.　SEM　images　showe　that　the　in　situ　composite　scaffold　possesses　interconnected　porous　structure　and　the　nano-particles　were　formed　in　situ　with　homogeneous　distribution　in　the　scaffold.　XRD　and　FTIR　confirm　the　ChS/CSA/nHAP　composite　scaffold　in　situ　formed　nano-HAP　crystals.　The　test　results　of　MTI-assay,　the　content　of　osteoblasts　protein　and　ALP　show　the　ChS/CSA/nHAP　in　situ　composite　scaffold　has　good　cytocompatibility.　The　ChS/CSA/nHAPin　situ　composite　scaffold　may　serve　as　a　good　scaffold　for　bone　tissue　engineering.