The invention provides a method for preparing a germanium nanometer array by inducing ionic liquid electrolytic deposition through a laser and belongs to the technical field of preparing methods of a germanium nanometer array. The problems that in the existing preparing methods of the germanium nanometer array, high temperatures are required, and the preparing technology is complex and toxic are solved. The method comprises the steps that the ionic liquid electrolytic deposition technology is used for being combined with the laser irradiation technology, green ion liquid 1-ethyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide which is free of toxin and pollution is used as a solvent, and Gecl4 serves as an electrolyte; and the electrolyte is irradiated by a pulse laser device, and the germanium nanometer array is prepared through one-step method electrolytic deposition. The preparing method is free of the requirement for the high temperatures, simple in technology, convenient to operate and each to achieve.