A spinal dynamic stabilization device is provided, including at least a main portion, at least a supporting structure, and a sliding bar. The main portion includes a guiding groove. The supporting structure includes two wing portions. The wing portions pivot on the main portion. The sliding bar connects to the supporting structure and moves in the guiding groove. When the sliding bar moves in the guiding groove, the wing portions expand rotatably toward the adjacent vertebrae of the spine of the patient by the sliding bar.