The invention discloses a method for positioning a fault between a converter transformer and a converter of a DC (direct current) ice-melting device, the method can optimize the prior art, the same subsections, rated current and protection delay are selected, and the over-current fault protection including the AC over-current fault protection and the DC over-current fault protection are separately realized. Compared with the method in prior art, the method provided by the invention adopts the logical criteria to fully judge the over-current fault of the DC ice-melting device, inner and outer faults in a protect zone can be effectively and accurately distinguished, the fault protection operates in protection zone, and the fault protection and the over-current protection do not operate outside the protection zone. Compared with the reliability and selectivity of the valve short circuit protection in prior art, the same of the over-current protection is ensured.