ABSTRACT Wood, as a natural material, inevitably contains initial defects such as knots, cracks, and decay, which are important factors affecting its mechanical properties and cannot be ignored. In order to investigate the influence of initial defects on the compressive mechanical properties of wood, Norway spruce was selected as the research object. Wood specimens without and with initial defects were prepared, and uniaxial compression tests were conducted. Combined with Digital Image Correlation (DIC) and finite element analysis, the compressive mechanical properties of defective wood were studied. The results showed that compared to defect-free specimens, specimens with defects exhibited a shortened elastic stage in the load-displacement curve, and the rate of decrease in load after reaching the peak was lower than that of defect-free specimens. For specimens of the same size, the compressive strength of specimens with defects was lower than that of defect-free specimens. The established finite element model could effectively simulate the compressive failure process of wood with initial defects, validating the effectiveness of numerical simulation. Bažant's size effect theory can be used for size effect analysis of the compressive strength of wood with initial defects in the longitudinal direction.