The invention discloses a nanometer flaky 1,1-diamido-2,2-binitro ethylene explosive and a preparation method thereof. The preparation method includes the following steps that a 1,1-diamido-2,2-binitro ethylene explosive and surfactant are dissolved in an organic solvent, heated and stirred to be completely dissolved, then cooling is conducted at the speed of 0.5-10 DEG C / min under stirring for crystallization, and through filtering, washing and drying, the nanometer flaky 1,1-diamido-2,2-binitro ethylene explosive can be obtained. The nanometer flaky 1,1-diamido-2,2-binitro ethylene explosive prepared through the method is of an orderly nanometer flaky structure and is uniform in particle morphology, the sheet layer diameter is 1-2 micrometers, the sheet layer thickness is 80-120 nm, the crystal purity of the explosive is larger than 99%, and important application prospects are achieved in the field of booster explosives and the like. The preparation technological process is simple, the preparation period is short, the solvent can be recycled, reaction conditions are moderate, and good safety is achieved.