At present, there are many detection methods of the grain pest, but these detection methods have many defects, such as low efficiency, poor accuracy, great implementation difficulty, detection not in time, etc. To solve the above defects, this paper provides a wireless sensor which can detect the species and quantity of the grain pest at the same time. Its main principle is: when pests go through ... [Show full abstract] detection electrodes of the sensor, its capacitance value will change. Due to different species of the grain pests have different dielectric constant, then, the change range is also different. According to different capacitance value range, the capacitance detection circuit determines the species of pests, and records the changing times of capacitance to determine the quantity of grain pests. The sensor has the advantages of the low power and the wireless transmission of the detection data and so on, and is suitable for large range of promotion. This has great significance on the China's grain safety.