The invention discloses a frequency-tracking and dynamically-arranged small-current grounding line selection system. The frequency-tracking and dynamically-arranged small-current grounding line selection system comprises a synchronous sampling module, a transmission module, a frequency tracking module and a grounding line selection module, wherein the synchronous sampling module is used for synchronously acquiring a voltage and current signal of a power grid and uploading the voltage and current signal to the grounding line selection module and frequency tracking module, the transmission module is used for achieving synchronous data transmission among the grounding line selection module, the frequency tracking module and the synchronous sampling module and is used for supporting dynamic arrangement of the whole system, the frequency tracking module is used for tracking a real-time frequency of a measurement power grid, the grounding line selection module is used for performing line selection algorithm analysis on the voltage and current signal acquired by the synchronous sampling module and judging a grounding branch. By the small-current grounding line selection system, a grounding circuit can be reliably, accurately and rapidly selected out in an arbitrary-frequency power grid, so that the running safety and reliability of the power grid is improved, the dynamic arrangement of the system can be achieved, and the applicability of the power grid is improved.