Abstract: In this paper, based on the coprime factorization in state-space, the necessary and sufficient condition of same-order strong stabilization is derived in state-space and a method has been given to design the same-order strong stabilizing controller. And then, it is proved that to simultaneously strongly stabilize 2 plants, i.e., to simultaneously stabilize 3 plants, is equivalent to simultaneously strongly stabilize an associated plant and its subplant,to simultaneously same-order strongly stabilize 2 plants is equivalent to simultaneously strongly stabilize an associated plant and its common subplant, and to simultaneously stabilize r+1 plants is equivalent to simultaneously strongly stabilize r-1 associated plants and their common subplant.