The invention belongs to the field of building materials and construction technologies and relates to nano foamed concrete, a reinforced insulation wallboard and a preparation method of the reinforced insulation wallboard. The nano foamed concrete disclosed by the invention is prepared from the following ingredients in parts by weight: 100 parts of cement, 0.1-5 parts of desulfurized oil coke ash residue, 0.012 part of waterproofing agent, 10-30 parts of fly ash, 0.1-6 parts of superplasticizer, 50-200 parts of water, 1-20 parts of foamer and 0.01-5 parts of nano wave absorbing agent. Thus, when a wallboard product, prepared by embedding steel wire meshes in the nano foamed concrete disclosed by the invention, is applied nearby airports, docks, navigation marks, television stations and receiving stations or applied to concrete-based retaining walls of electromagnetic wave interference preventing scientific research departments, precise instrument plants and information leakage prevention high-grade buildings of national confidential units and the like, the most basic physical, mechanical, heat preservation and heat insulation properties are guaranteed on one hand, and the wallboard product has the capabilities of lowering noise and insulating sound on the other hand.