The invention relates to a preparation method of a nanometer-cube-accumulated layered mesoporous FeMoO4 solid material. The method specifically comprises dissolving a certain amount of an iron-containing compound, a molybdenum-containing compound and a homogeneous precipitant urea into a certain amount of a solvent; performing full stirring for a certain time to form a stable solution; transferring the mixed solution into a stainless steel high-temperature high-pressure reaction kettle containing a polytetrafluoroethylene lining; performing a hydrothermal reaction; performing heating at a temperature in a range of 120-180 DEG C for 12-24 hours; performing cooling to a room temperature; washing an obtained product by deionized water or absolute ethyl alcohol for three times or more; performing centrifugal filtration; and performing vacuum drying at a temperature in a range of 50-60 DEG C; performing calcining on an obtained product in an air atmosphere to obtain the nanometer-cube-accumulated layered mesoporous FeMoO4 solid material.