With non-aqueous electrolyte as the medium, a non-destructive electrolytic method has been adopted to extract inclusions from spring steel. An electrolytic experiment has been carried out on the steel samples at the beginning of the LF refining and at the end of the calcium treatment in the process of smelting 51CrV4 spring steel in a steel enterprise, followed by an examination of the morphology, size and composition of the inclusions by scanning electron microscopy (SEM) and energy spectrum analysis. The results show that the inclusions are mainly irregular polygons in shape, with the average size about 25 μm at the beginning of LF refining, which are transformed into spherical shapes after the calcium treatment, with the average size reduced to 14 μm. It has also been found that there is a concentration of CaS with a high melting point on the surface of inclusions, indicating that the calcium content tends to be very high in the process of calcium treatment, which should be properly reduced in the process of smelting.