In order to enhance the speed and precision of grain moisture content measurement, and to satisfy the need of online detection of drying machinery, a new symmetric needle typed moisture content sensor which direct thrust into the grain was proposed, which was cooperated with high precision testing circuit and optimization algorithm, and the corresponding new equipment was designed. The trial results indicated that the error of paddy moisture content measurement was no more than 1% and the response time was less than 2 s. Through simple parameters setting, this equipment could be applied to measure moisture content of other grains. Through this new method, a new online measurement scheme was put forward.