In　this　study,　wooden　components　torn　down　from　ancient　buildings　were　used　as　the　experimental　materials.　With　methodology　based　on　reverse　simulation　testing,　some　artificial　holes　making　up　different　proportional　areas　of　their　cross-section　were　chiseled　and　tested　with　a　six-sensor-point　stress　wave　testing　device.　The　results　indicated　that　two-dimensional　analog　images　could　be　used　to　judge　the　internal　defects　of　wooden　components　qualitatively　but　did　not　provide　quantitative,　accurate　determination.　By　comparing　and　contrasting　the　attenuation　tendency　of　stress　wave　velocities　among　adjacent　sensor　points,　separated　sensor　points,　and　diagonal　sensor　points,　the　defect　grade　of　wooden　components　can　be　classified.　Six　variations　were　chosen　as　discriminant　factors.　These　were　the　attenuation　coefficients　of　the　stress　wave　velocities　via　three　propagation　paths　and　the　relative　proportions　of　their　absolute　values.　The　Mahalanobis　distance　discrimination　model　was　adopted　for　the　in-grade　estimation　of　the　internal　defects　present　in　the　component＇s　cross-section.　This　method　had　high　operability　and　no　misjudgment　ratio.