Abstract: Moisture moving in grain kernel and partial distribution of high moisture grain in the coil affected measured value of moisture content of grain by using high frequency coil. In the case of instability state after dried by ventilation，while moisture moved from inside to outside of the kernel, moisture content of grain measured by using high frequency coil system was larger than the value measured by using heated drying method. On the surface of grain kernel, if the free water was increased by spraying, measured moisture contents increased much with the increasing of quantity of spraying water. It is found that even if high moisture grain was unbalancedly loaded in the coil, measured moisture content was not affected.