Atomic　force　acoustic　microscopy　(AFAM)　has　been　developed　in　order　to　evaluate　mechanical　properties　of　the　materials　at　nano-scale.　The　SiOx　films　on　the　silicon　wafer　and　glass　slide　were　prepared　by　plasma　enhanced　chemical　vapor　deposition　(PECVD)　and　their　properties　were　characterized　by　atomic　force　acoustic　microscopy　(AFAM).　The　images　of　the　amplitude　of　the　vibrating　cantilever　were　visualized　for　the　sample　vibrating　at　the　ultrasonic　frequency　and　the　characteristics　of　the　images　were　also　discussed　at　the　different　excitation　frequencies　The　results　showed　that　the　acoustic　amplitude　images　can　provide　information　about　the　local　elasticity　and　the　subsurface　defects　of　the　materials　qualitatively　(C)　2010　Published　by　Elsevier　Ltd