The invention relates to a three-stable state implementation method of a fully-flexible five-rod mechanism. The three-stable state implementation method is characterized in that the fully-flexible five-rod mechanism at least comprises a rack, a drive rod, a left connecting rod, a right connecting rod, a connecting rod rack, a left lower flexible hinge, a left upper flexible hinge, an upper flexible hinge, a right upper flexible hinge and a right lower flexible hinge, wherein the rack and the drive rod are connected through the left lower flexible hinge; the drive rod and the left connecting rod are connected through the left upper flexible hinge; the left connecting rod and the right connecting rod are connected through the left upper flexible hinge; the right connecting rod and the connecting rod rack are connected through the right upper flexible hinge; and the connecting rod rack and the rack are connected through the right lower flexible hinge. The fully-flexible five-rod mechanism is simple in structure, is low in manufacturing cost, is free from friction, is free from abrasion, is capable of being processed in a single-piece manner, is precise to position, and can be used for equipment such as a precise positioning platform, a multiple-way optical switch and the like.