The invention discloses a 
copper germanic acid nano wire and a preparation method thereof, belonging to the technical field of nano material preparation. The 
copper germanic acid nano wire consists of single-
crystal copper germanic acid core and a very thin amorphous copper germanic acid casing covered on the external layer. The preparation method takes 
germanium dioxide and sheet copper as 
raw material and water as a 
solvent, wherein, the sheet copper is also used as a deposition substrate. The preparation method comprises the steps of: ultrasonically cleaning the sheet copper in 
distilled water for 10 minutes, fixing the sheet copper in a reaction kettle vessel, uniformly stirring the sheet copper, insulating heat for 0-24 hours under the temperature of 200-500 DEG C and the pressure of 1-15MPa, and finally obtaining the copper germanic acid nano wire on the sheet copper. The preparation method has the advantages of free growth template addition, simple preparation process, easy operation and control, low growth temperature and lower preparation cost. In addition, as the method adopts the processes of innocuous 
germanium oxide and hydro-deposition, the 
raw material and the preparation process are harmless to the environment, therefore, the requirement of 
environmental protection is met. The preparation method can realize the 
mass preparation of the copper germanic acid nano wire.