To effectively detect the local defects of wood structure components, the finite element method (FEM) and experimental modal analysis (EMA) were empl oyed to generate the first displacement mode shape of wood beams. Then the displ acement mode shape was used to compute modal curvature by using the central diff erence method. The change of modal curvature before and after damage in wood bea ms was compared. Different severities, locations and the number of damage were s imulated by digging a hole in the intact wood to verify the modal curvature gene rated by both FEM and EMA. The results show that modal curvature is a sensitive parameter to wood damage. It is feasible to quantitatively detect the location, severity and number of damage. Meanwhile, modal analysis technology was proved a good way to nondestructively evaluate the damage in wood beams.