As　a　mussel-inspired　polymer,　polydopamine　(PDA)　coating　can　be　used　as　a　simple　and　universal　way　to　form　nano-hydroxyapatite　(nHAP)　crystals　on　a　variety　of　substrates.　Therefore,　PDA　is　widely　used　in　the　preparation　of　bone　repair　materials.　However,　its　uneven　distribution　and　easy　degradation　under　strongly　alkaline　con-ditions　limit　its　application.　Therefore,　based　on　the　principle　of　in　situ　regeneration,　this　study　combined　the　freeze-drying　technology　with　the　diffusion　method　of　ammonium　carbonate　to　bionics　construct　porous　micro　-nano　composite　scaffolds.　Chitosan　(CS)　and　dopamine　hydrochloride　(DA)　were　used　as　the　chief　components　to　form　a　multilayer　layered　scaffold　structure.　PDA　and　nHAP　grow　in　situ　on　the　surface　of　the　freeze-dried　scaffolds　after　ammonium　carbonate　gas　diffusion　treatment　and　Tris　buffer　immersion.　The　mild　synthesis　method　effectively　avoided　the　decomposition　of　PDA,　and　the　gas　diffusion　method　promoted　the　uniform　distribution　of　PDA.　The　effect　of　PDA　on　nHAP　formation　was　studied　by　adjusting　the　amount　of　DA.　The　cross　-linking　reaction　between　PDA　and　CS　was　verified　by　FTIR　and　XPS.　Surface　morphology　was　observed　by　SEM.　The　formation　of　nHAP　was　confirmed　by　XRD.　The　scaffolds　had　good　porosity,　degradation,　water　absorption,　thermal　stability　and　biomimetic　mineralization　properties.　Cell　experiments　showed　that　the　scaffolds　had　good　biocompatibility　and　had　no　toxicity　to　cells.　The　construction　of　bone　defect　animal　model　further　verified　that　the　scaffolds　promoted　bone　regeneration　in　the　defect　site　of　the　body.　This　study　provided　a　new　idea　and　method　for　the　preparation　of　bone　repair　scaffolds.