β-Amyloid　(Aβ)　plaque,　representing　the　progressive　accumulation　of　the　protein　that　mainly　consists　of　Aβ,　is　one　of　the　prominent　pathological　hallmarks　of　Alzheimer＇s　disease　(AD).　Label-free　imaging　of　Aβ　plaques　holds　the　potential　to　be　a　histological　examination　tool　for　diagnosing　AD.　We　applied　label-free　multiphoton　microscopy　to　identify　extracellular　Aβ　plaque　as　well　as　intracellular　Aβ　accumulation　for　the　first　time　from　AD　mouse　models.　We　showed　that　a　two-photon-excited　fluorescence　signal　is　a　sensitive　optical　marker　for　revealing　the　spatial-temporal　progression　and　the　surrounding　morphological　changes　of　Aβ　deposition,　which　demonstrated　that　both　extracellular　and　intracellular　Aβ　accumulations　play　an　important　role　in　the　progression　of　AD.　Moreover,　combined　with　a　custom-developed　image-processing　program,　we　established　a　rapid　method　to　visualize　different　degrees　of　Aβ　deposition　by　color　coding.　These　results　provide　an　approach　for　investigating　pathophysiology　of　AD　that　can　complement　traditional　biomedical　procedures.　©　2019　The　Authors.