The invention relates to an ADN / A1 / MxOy-based nano composite energetic material and a preparation method thereof, the method comprises the following steps: dissolving metal (M) salt in a solvent to prepare a solution with a certain mole concentration, weighing an oxidizing agent ammonium dinitramide (ADN) and adding in the above solution, stirring until the solution is in a transparent, respectively adding a fuel nano aluminium powder and a proton trapping agent, stirring for 10-20 minutes, standing and aging for several days, and performing supercritical drying by carbon dioxide, and obtaining the ADN / A1 / MxOy-based nano composite energetic aerogel. The preparation method has the advantages of strong operationality, controllable proportion of oxidizing agent to fuel and simple required equipment, the obtained product has the advantage of good safety performance, is suitable for amplification production, and provides thinking for development of the future energetic material, the ADN / A1 / MxOy-based nano composite energetic material can completely or partially replace the current dangerous and complex energetic material possibly, and is an important direction for development of the nano energetic materials such as solid propellant, and explosives and powders.