A reinforced skin-core inter-miscible composite board and a preparation method therefor, belonging to the technical field of foam reinforced boards. The composite board comprises, from top to bottom, an elastic surface layer, a reinforced continuous transition layer, and a reinforced hard foam core layer; the reinforced hard foam core layer is a hard foam material reinforced by a porous framework; the reinforced continuous transition layer is a transition layer reinforced by a reinforcing net, and the reinforcing net is at least laid flat inside the transition layer; the transition layer is an integrated structure formed by mutual infiltration and curing of a raw material which constitutes the hard foam material, is not completely cured and still has fluidity, and a raw material which constitutes the elastic surface layer and is not completely cured. The hard foam core layer, after being reinforced by the porous framework, can significantly increase the compressive strength of the composite board, and the composite board can provide better support for the weight loaded on the board surface, so as to avoid the problem of board surface collapsing.