Based on the measuring principle of electrical resistance method for moisture content, an innovative measuring system was proposed with some key technologies including improving the signal quality through a conversion from the resistance measurement to the frequency measurement, using data fusion to take the time-variable temperature effect into account and designing an intelligent algorithm to solve the nonlinear fitting to the measured data. The new system and correspondingly developed device can get rid of the disadvantages of conditional resistance method and find an optimum application to the grain drying. The intelligent real-time on-line measuring system is featured with high accuracy, good flexibility and simple architecture.