Abstract: The law of temperature distribution inside wood using Pinus massoniana as experimental material had been researched during microwave-vacuum drying for the first time. The results showed that, with a certain scope of radiation power(160 kW/m³)and wood thickness(60 mm), temperature distribution inside wood was uniform, and there was not regular temperature gradient along the direction of wood thickness; the inner temperature difference of wood presented a growing trend in the last period of drying; during microwave-vacuum drying, inner temperature difference of wood was caused by microwave field and the differences of dielectric characteristics among different locations in wet wood, and this kind of non-uniformity existed locally in wood.