The invention discloses a deep-thin hole chrome-plating anode and a preparation method thereof. The prepared anode comprises a steel wire. One end of the steel wire is a pier head. The pier head end of the steel wire is provided with a positioning sleeve. A copper layer with a unilateral thickness of 0.04-0.08mm is plated on the outer surface of the steel wire. A lead layer or a lead-tin alloy layer with a unilateral thickness of 0.15+/-0.025mm is plated on the copper layer. Knurled recesses are formed in the plated section of the steel wire. The anode can be prepared through the following steps: recesses are formed in the steel wire through knurling; the positioning sleeve is arranged behind the pier head in a sleeving manner; the copper layer is plated; and the lead layer or the lead-tin alloy layer is plated. The anode can also be prepared through the following steps: the positioning sleeve is arranged behind a round steel wire pier head; the copper layer is plated; the lead layer or the lead-tin alloy layer is plated; and recesses are formed in the lead or lead-tin alloy layer through knurling. With the knurled recesses in the deep-thin hole chrome-plating anode provided by the invention, the surface area and cross-section area of the anode are increased, so that the one-time chrome-plating qualification rate of pipe fittings with small and deep hole diameters is improved by 50%.