In　this　study,　we　propose　nondestructive　testing　methods　and　combined　forecasting　models-based　stress　wave　and　impedance　measurements　to　obtain　accurate　internal　defects　information　for　wooden　building　components.　Internal　defects　data　for　major　wooden　components　of　an　ancient　building　in　China　and　reverse　laboratory　test　data　on　matching　tree　species　indicated　various　degrees　of　damage　on　the　pavilion　wood　structure　surface　and　internal　defects　in　certain　pillars.　The　stress　wave　method　enabled　rapid　acquisition　of　two-dimensional　plots　of　test　sections;　however,　the　results　revealed　that　the　area　of　stress　wave　detection　was　greater　than　the　actual　defect　area.　Moreover,　the　impedance　meter　was　able　to　determine　the　defect　position　and　type　in　a　single　path,　and　the　actual　defect　area　was　proportional　to　the　absolute　error　of　the　drilling　resistance.　By　distributing　the　errors　from　the　two　nondestructive　testing　methods　on　the　basis　of　a　Shapley　value　algorithm,　we　determined　the　weights　of　stress　wave　and　impedance　meter　data　in　the　forecasting　models　and　established　combined　forecasting　models　that　showed　greater　accuracy　with　a　mean　relative　error　of　less　than　6%.　This　method　can　improve　the　prediction　accuracy　of　internal　defects　in　ancient　buildings　and　provide　effective　data　support　for　practical　engineering　repair　and　reinforcement　schemes.