The invention relates to a small-current grounding fault positioning software implementation method, and the method comprises the following steps: S1, adding one positioning service software module in a distribution automation main station operating on site; S2, carrying out the collection of the small-current grounding fault information through the distribution automation main station, and transmitting the collected information and the line topological information to the positioning service software module; S3, enabling the positioning service software module to carry out the positioning of the grounding fault through a transient waveform similarity method, and displaying the positioning result on the distribution automation main station. The method achieves the positioning of the small-current grounding fault on a conventional distribution automation main station, solves a problem that a conventional distribution automation main station cannot process the grounding fault, and greatly improves the power supply reliability.