The invention discloses a small current grounding line selection and phase selection method based on fault sequence components. The method comprises the following steps: (1) collecting a zero sequencevoltage of a bus, and starting grounding line selection judgment when the zero sequence voltage exceeds a set threshold; (2) extracting a three-phase current component in a line, and calculating thesizes of corresponding positive sequence, negative sequence and zero sequence components, respectively; and (3) constructing a relational expression group based on the current components and the sequence components thereof calculated in the step (2), and judging a fault line and a fault phase of the line in sequence according to the result. According to the small current grounding line selection and phase selection method disclosed by the invention, the grounding line selection judgment is not relied on the zero sequence current, line selection and phase selection can be performed just by using the own three-phase current of the line, thereby avoiding the situation of line selection errors due to the wrong secondary circuit wiring, and meanwhile, eliminating the influence of the own imbalance of the system and the load size of the line on the line selection judgment, and effectively improving the accuracy of the grounding line selection, so that the small current grounding line selection and phase selection method has a broad application prospect.