A real-time inertial navigation system (INS) for mobile miniature robots was proposed, which mainly consists of hardware platform and software system. Based on the principles of embedded system, and by use of MEMS-based inertial measurement units (IMU) and micro control units (MCU) including ARM and CPLD, a compact, low-power-consumption, low-cost, and universal real-time hardware platform was constructed for the navigation system. Besides, a μC/OS-II real-time operating system was transplanted for software developing, where all the algorithms of digital signal processing, data interpolation, navigation calculating were realized. Furthermore, a fuzzy system was designed for sensor data fusion so as to achieve accurate navigation. Finally, the MEMS-based INS was fully tested via experiments on a mobile miniature robot. Experiments results show that average error of the heading angle estimation is about 0.56%, average error of Attitude angle estimation is 2.57%, and the maximum error of plane position is about 10%, which indicates that this INS satisfies requirements of mobile miniature robots.