Most　of　imaging　algorithms　used　in　guided　wave　arrays　share　the　same　assumption　that　the　signal　scattered　from　defects　will　propagate　uniformly　in　all　directions.　However,　some　recent　researches　on　scattering　properties　of　guided　wave　in　defects　demonstrate　that　the　scattered　signal　is　un-uniform　even　for　a　circular　hole.　Scattering　properties　of　defects　were　studied　and　effects　of　sensors　distribution　strategies　were　presented　in　this　paper.　A　3D　FE　model　was　employed　to　study　the　sensor　arrangement　method　and　two　basic　imaging　methods　ellipse　and　hyperbola　algorithm　was　used.　Experiment　was　implemented　in　a　3mm　aluminum　plate　with　piezoelectric　elements.　Results　show　that　for　crack-like　defects　and　through-hole,　both　ellipse　and　hyperbola　imaging　algorithms　were　valid.　The　number　and　position　of　transducers　affect　the　accuracy　of　crack　imaging.　To　detecting　different　kinds　of　defect　the　preferable　array　arrangement　should　be　set　according　to　the　scattering　characterization　of　defect.　©　(2013)　Trans　Tech　Publications,　Switzerland.