Experimental study on microwave drying of thick layer brown rice with concurrent flow ventilation was carried out. The results showed that with the increase of microwave radiation power level, the grain temperature and drying rate increased. If microwave power is controlled at 0.05～0.09 kW/kg, and superficial air velocity at 0.12～0.20 m/s, the quality of the products is not seriously affected. The most effective drying thickness of brown rice layer is about 0.130 m under this drying condition. It is slightly larger than that of microwave drying of thick layer rough rice. Because of this, the efficiency of microwave drying of brown rice could be higher than that of rough rice.