Abstract: In order to further enhance the speed and precision of grain moisture content measurement, and to satisfy the need of online detection of harvest machinery, a new and fast measurement technology for grain moisture content based on Digital Signal Processor (DSP) and Micro-Processor Unit (MPU) was proposed, and the corresponding new system equipment was designed. As a case example of grain, soybean was selected as the test material. The trial results indicated that the error of moisture content measurement was less than 1% and the system could run more than 15 times per minute. The equipment has also obligated bigger storage space, which can be applied to measurement of other grain moisture contents. The testing proves that the performances of the measuring accuracy, measuring speed and temperature stability of the newly developed equipment are better than those of the existing sets. Through the new method, an accurate and high speed online measurement scheme was put forward.