The water diffusion characteristics of drying dioscorea opposite during by far infrared were investigate. The dehydration of Dioscorea opposite by Far-infrared drying equipment. The technology of low field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) were applied to measured moisture content of D. opposite during drying. Comprehensive consideration results of LF-NMR, MRI, drying curve and drying rate. Water diffusion characteristics of D. opposite with different slice thickness (4, 8, and 12 mm) during drying were analyzed, and the thin-layer drying were modeled. The results showed that the drying rate shortly and rapidly increased and then gradually decreased. The drying time of 4 mm thick D. opposite was 36.33% and 53.33% shorter than that of 8 mm and 12 mm respectively. The peak of T₂ were moves to the left and its area decreased. Free water was depleted during drying. At the end of drying, the internal moisture of D. opposite was mainly bound water (87%) and a small amount of weak bound water (13%). Water inside of D. opposite has density gradient, and moisture migrated from high to low density zone. Decreasing the thickness of D. opposite properly could promote the decrease of H⁺ proton density and improve the drying efficiency. Page model fitted well (R²＞0.9), it could characterize and predict the process of drying D. opposite by far infrared well. In conclusion, the results provided the theoretical basis for the selection of material thickness and the prediction of drying process of D. opposite.