The invention discloses a nanocrystalline wood floor geothermal composite structure, comprising an extruded sheet thermal-protective coating and a heat conduction floor layer. The technical key points are as follows: the upper part of the extruded sheet thermal-protective coating is evenly provided with closed grooves, the upper part of the extruded sheet thermal-protective coating and the closed groove positions are respectively distributed with a heat conduction layer evenly, a heating cable is paved in the closed groove with the heat conduction layer, and the upper part of the heat conduction layer is directly paved with the heat conduction floor layer with a wear-resistant surface course. The composite structure is not manufactured by lyophobic materials, thus having waterproof function. When in use, a user can set the temperature by proper motion as required, and especially at night, night off-peak electricity is introduced for warming, thus alleviating the peak electricity conflicts of a grid transmission system, replacing a coal-fired boiler and satisfying large area heating. The invention also has the characteristics of simple and reasonable structure, environment protection without pollution, small occupied area, low heating cost, long service life, wide application range, capability of being widely used indoor and outdoor and the like.