It　is　currently　known　that　using　stress　wave　and　drilling　resistance　to　detect　the　internal　damage　in　the　ancient　timber　structure　is　not　a　highly　precise　process.　To　improve　the　detection　precision　of　this　process,　a　simulation　test　was　used　to　detect　the　internal　damage　of　poplar　and　elm　in　ancient　buildings.　In　this　empirical　study,　we　compared　the　detection　precision　of　these　two　detection　methods.　Based　on　the　idea　of　variable　weight,　we　introduced　three　combined　forecasting　models　based　on　the　IOWA　operator,　IOWGA　operator,　and　IOWHA　operator　to　predict　the　internal　damage　in　the　ancient　timber　structure.　The　results　show　that　the　combined　forecasting　model　based　on　the　IOWA　operator　is　more　effective　in　predicting　compared　to　a　single　detection　method　and　other　combined　forecasting　models.　To　be　more　specific,　the　results　show　that　the　detection　precision　of　the　combined　model　is　increased　by　25.8%　and　4.7%,　respectively,　compared　to　the　precision　of　the　stress　wave　and　drilling　resistance　tests.　The　error　indicators　of　the　combined　forecasting　model　based　on　the　IOWA　operator　are　better　than　those　of　the　other　combined　forecasting　models.　In　addition,　the　analysis　results　based　upon　cross-validation　theory　show　the　combined　forecasting　model　based　on　the　IOWA　operator　has　the　best　applicability,　which　provides　a　new　practical　method　for　evaluating　internal　damage　of　timber　components　in　ancient　buildings.