A 3D micro-electromechanical systems (MEMS) foldable structure for Micro-IMU application is proposed, which is composed of SOI substrate, polyimide flexible chain, metal wires and MEMS multi-ring gyroscope. In this paper, the feasibility of foldable structure and sensors is analyzed based on finite element method. Based on SOI integrated MEMS technology, the fabrication process of core sensor and foldable structure technology are integrated. The structure is equipped with a single-axis disk multi-ring MEMS gyroscope, and the flexible hinge is used to realize the 3D folding of the structure and the electrical interconnection between the sensors. A 3D foldable system with a volume of 1cm3 and a mass of 250mg was fabricated.