The invention discloses a preparation method for a platinum nanowire. The preparation method comprises the following steps of: preparing a platinum precursor solution, adding a surfactant, enabling platinum ions to enrich on a glass substrate template under action of electric fields, adding a reducing agent to reduce to obtain nao particles; and then, re-adding the precursor solution, applying electric fields in the perpendicular direction and adding the reducing agent, enabling platinum ions to move and grow in an orientated mode, and adding the reducing agent under action, thereby obtaining the platinum nanowire which is high in length-diameter ratio and is regular in orientation.