The invention discloses a metal nanometer wire, dispersion liquid and a preparation method of the metal nanometer wire and the dispersion liquid. The preparation method of the metal nanometer wire comprises the following steps that (1), a metal ion solution with the concentration being 0.01-1 mol/L is prepared, a complexing agent and a nucleating agent are added, the pH value is adjusted to be 10.0-13.5 through an alkali solution, and a solution A is prepared, wherein the metal ions are magnetic metal ions or a mixture of the magnetic metal ions and nonmagnetic metal ions; (2), a reductant solution with the concentration being 0.1-3 mol/L with a strong reducing property is prepared, the pH value is adjusted to be 10.0-13.5 through adjustment of the alkali solution, and a solution B is prepared; (3), the solution A and the solution B are placed in a reactor to be fully mixed, a reaction is performed in the conditions that the temperature is 50-100 DEG C, and the magnetic field strength is 0.005-1 T, the reaction is ended before the agglomeration phenomenon occurs, and a reaction stock solution containing the magnetic metal nanometer wire or an alloy nanometer wire is prepared. The preparation method is low in reaction temperature, and the prepared one-dimensional metal nanometer wire is high in electrical conductivity and wide in size adjustable range.