The invention discloses a magnesium cement lightweight aggregate concrete hollow box board composed of magnesium cement lightweight aggregate concrete, reinforcing steel bars and a lightweight composite box. The dry apparent density of the magnesium cement lightweight aggregate concrete is 1800-1950kg/m<3> and 15% to 30% less than that of ordinary concrete and the strength of the magnesium cement lightweight aggregate concrete can reach common strength grades of ordinary concrete. By means of the magnesium cement lightweight aggregate concrete hollow box board, the structural self-weight can be reduced, the use amount of concrete can be saved, and the overall cost can be reduced; furthermore, the seismic response force, floor shear force, bending moment, the maximum floor displacement and the like of the structure can be reduced, so that every mechanical performance can meet standard requirements. The magnesium cement lightweight aggregate concrete hollow box board has good fireproof, acoustic insulation and thermal insulation performance, obvious energy-saving and thermal insulation effects and good economic, social and environmental protection benefits and is suitable for large-scale application to large-span bridge structures, high-rise buildings and marine engineering.