The invention belongs to the field of polyurethane, and concretely relates to a polyurethane combined material for furniture sponge and a preparation method thereof. The combined material is prepared by mixing a composition A and a composition B, the composition A is prepared from polyether polyol, polymer polyol, a cross-linking agent, a foaming agent, a foam stabilizer , a pore-opening agent and a catalyst, and the composition B is prepared from polyether polyol, an isocyanate and a pore-opening agent. When the combined material is used, the composition A and the composition B are mixed according to the weight ratio of 100:75-110 and injected into a die, so that high-bearing low-density furniture sponge is prepared. The combined material employs low-volatilization low-atomization raw materials, and possesses advantages of low smell, good fluidity, wide applicable temperature scope and the like. The furniture sponge prepared from the combined material possesses the advantages of being basically odorless, safe, nontoxic, free of defects on the surface, good in elasticity, excellent in handfeel, low in density, good in bearing property and the like. The invention also provides a preparation method for the combined material, and the technology is reasonable.