The invention discloses a preparation method of two-dimensional nano-graphene. The method includes: mixing acrylic acid and water according to the volume ratio of 1:1-1:2, adding hydrotalcite particles passing a sieve 20-50 in mesh into acrylic acid solution according to the quantity that each gram of hydrotalcite corresponds to 3-5mmol of the acrylic acid, stirring at the temperature of 60-70 DEG C, ageing, separating particles, adding the particles into isopropanol solution, adding ammonium persulfate, heating to 60-90 DEG C for reaction for 8-10h, drying at the temperature of 70-90 DEG C, grinding, and passing a sieve 20-40 in mesh to obtain powder; heating the power to 600-700 DEG C in vacuum, calcining for 2-4h, adding calcined powder into hydrochloric acid solution 20%-40% in concentration, stirring under the protection of nitrogen, precipitating, separating and drying; and heating an obtained product to 2000-2500 DEG C in vacuum, subjecting the product to heat treatment for 3-6h and cooling so that the two-dimensional nano-graphene is obtained. The method is simple in material sources and simple and mild in process.