<p>This study quantitatively examines the impact of wood micro-density and inhomogeneous moisture distribution on heat transfer during microwave treatment. A method for the quantitative analysis of micro-density and moisture was developed, and a mathematical model was constructed to describe the uniform and non-uniform heat transfer in wood subjected to microwave heating. A corresponding numerical simulation program was developed, and its accuracy was validated using experimental data. The findings indicate that pore volume in poplar significantly decreases from earlywood to latewood by 43.99%, and the micro-density and moisture of the wood exhibited a non-uniform distribution along the radial direction, and this non-uniform characteristic affected the microwave absorption power and the rate of temperature increase during the microwave preheating process of the wood. The non-uniform model more accurately predicts the dynamic temperature distribution within wood under varying moisture conditions compared to the uniform model, thereby improving prediction accuracy by over 65%. Furthermore, wood with a moisture content between 40 and 50% heats most rapidly during microwave treatment. This research offers valuable theoretical insights for industrial applications, such as microwave drying and the modification of wood.</p>