To　evaluate　the　interior　voids　in　wood　components,　the　stress　wave,　a　nondestructive　testing　technology　was　used　to　assess　fir　wood.　The　stress　wave　images　were　analyzed.　The　attenuation　of　the　stress　wave　propagate　through　different　voids　areas　were　measured.　In　order　to　reduce　the　prediction　error　of　discrimination,　the　Mahalanobis　distance　was　proposed　to　detect　the　degree　of　voids.　The　results　showed　that　the　location　of　interior　voids　was　detected　through　the　stress　wave　images.　According　to　the　concept　of　Mahalanobis　distance,　five　paths　were　used　to　analyze　the　attenuation　law　of　the　stress　wave　through　different　interior　voids　areas.　A　discrimination　model　was　established　to　evaluate　the　degree　of　the　interior　voids　in　the　wood　components.　The　stress　wave　not　only　detected　the　voids　of　small　area　voids,　but　also　assessed　the　large　area　interior　voids.　The　method　improves　the　measurement　precision　of　the　location　and　the　area　of　the　interior　voids　in　the　wood　components,　as　well　as　provides　a　basis　for　the　prevention　and　detection　of　the　interior　voids　in　the　wood　structures.　©　2022,　Editorial　Office　of　Chinese　Journal　of　Wood　Science　and　Technology.　All　rights　reserved.