Abstract: An accurate and on line method of measuring moisture content of flowing grain would be useful for the keeping up grain qnality and the automation of grain harvesting and drying processes. A procedure for measuring instantaneous sound pressure level of flowing grain was developed. Experiments were performed to determine the relationships between measured acoustic information and moisture content of grain samples. The amplitude-frequency response curve as a function of moisture content was modelled. Based on the acoustic method a flow sound grain moisture content meter was designed. Tests were performed on wheat of Jing411 and maize of Nongdai60. Results were Satisfactory.