When wood is dried below the fiber saturation point, moisture primarily undergoes non-steady-state diffusion. To establish a foundation for wood drying, this study employs the non-steady-state method. The moisture diffusion coefficient of birch wood was determined under specific experimental conditions, based on a drying reference. Computational Fluid Dynamics (CFD) simulation was employed to validate the findings. The results show that under the combined influence of moisture content and temperature, the moisture diffusion coefficients of birch wood are 2.36×10− 5cm2/s,2.09×10− 5 cm2/s,1.88×10− 5 cm2/s and 1.63×10− 5 cm2/s. The integration of moisture diffusion coefficient calibration and wood drying simulation enables more precise prediction of moisture migration behavior in birch wood. The simulation results demonstrate that calibrating the moisture diffusion coefficients enhances the accuracy of wood drying simulation and offers valuable theoretical guidance for wood drying processes.