The invention relates to a method for preparing a nanometer layer on the surface of a metal material with a plane or any curved surfaces by explosion. The method is characterized in that: explosives are used as energy, and impact loads generated by the explosion of the explosives act on the back of the material, so that the material impacts a rigid base at a speed of more than 600 m/s to trigger the surface of the metal material which impacts the base to generate the nanometer layer, wherein the pressure of an impact point is more than 10 GPa. The method has the characteristics of simple production device, high preparation efficiency, large preparation area, suitability for industrial application and the like, and the generated nanometer layer hardly falls off, so the aim of improving the performance of the surface of the engineering metal material is fulfilled.