<p>Wooden buildings are constructed using wood as the main building material. Because of the inherent properties of wood drying shrinkage and swelling, wooden components inevitably experience aging during long-term service, directly affecting the ignition and combustion of wooden structures. This study acquired batches of wood with different thicknesses undergoing dry–wet alternate aging through simulated experiments of artificially accelerated dry–wet alternating aging of wood. In addition to, through cone calorimeter combustion experiments, the combustion characteristics of wood with different degrees of dry and wet aging under the influence of thickness were analyzed, and the changes in main combustion parameters, including ignition time, mass loss, heat release, smoke production rate, etc., were compared. Meanwhile, the influence of thickness on the combustion characteristics of dry–wet aging wood was discussed by analyzing the characteristic peaks of different combustion stages, revealing the influence of thickness on the combustion characteristics of dry–wet aging wood. The research results indicate that the evolution law of heat transport in wood pores caused by aging determines whether there will be sudden changes in aging degree during combustion, while the thickness effect caused by thickness changes determines how many times the sudden changes in aging degree occur under dry–wet alternation. The research results aimed to render theoretical support for the fire hazard assessment of wooden structures.</p>