The characteristics of mechanical gyroscope are high technology, complicated structure and restrict precision. Basing on this aspect, MEMS gyroscopes and accelerometers are adopted as the inertial measurement unit in this paper. S3C2440 of the ARM9 series is taken as the micro processing chip to design a system of north seeking to complete measurement, transmission, and processing and so on. MEMS sensor can reduce the influence from external environment factors on the north-seeking accuracy. ARM chips can finish collecting data and processing effectively, while the system structure could be achieved easily.