A grain moisture measuring method based on DSP is studied. First, the grain is leaded-in measuring capacitance by gravity. Secondly, the grain moisture is measured through MCU and DSP, and the measured data are stored or displayed on LCD. Finally, the measured grain is ejected by a discharging screw feeder, and a measuring cycle is finished. A DS18S20 is adopted to detect and compensate the temperature in the process of measuring grain moisture. The measuring precision is higher than 1% RH, and exceeds the conventional measurement methods.