Poplar veneer/straw board composites with flame retardation and smoke suppression were prepared with rice straw and poplar veneer as raw material, and inorganic adhesive as binder. Two kinds of composites of veneer/single straw board core layer and veneer/double straw board core layer were designed. The flame retardation and smoke suppression performance of inorganic poplar plywood, straw board and veneer/straw board composites was studied by comparing the combustion performance, mass loss rate and thermal conductivity. The mechanical properties of the composites were also compared. The results show that inorganic adhesive plays a very good role in flame retardancy by covering the board surface and cutting off the transfer of oxygen and heat, so as to protect the internal plate. Veneer/straw board composites can guarantee the structure and strength of board, and reduce the risk of fire. Compared with veneer/single straw board core layer composite, the thermal conductivity of veneer/double straw board core layer composite is reduced by 27.7%. The static bending strength and elastic modulus of veneer/double straw board core layer composite are improved significantly, and it can prevent the break edge phenomenon of floor board.