The invention discloses a direct-current line rapid protection method and system. The method comprises the steps of: starting high-sensitivity protection when a dual-tree complex wavelet transform decomposition amount corresponding to an obtained direct-current voltage meets a preset high-sensitivity protection starting criterion; if the current direct-current voltage meets the preset abnormal large-number locking criterion, performing locking protection; and if the dual-tree complex wavelet transform decomposition amount corresponding to the current DC voltage meets a preset fault criterion,protecting an action outlet. According to the invention, after high-sensitivity protection is started, if a bipolar fault sub-criterion is met, the bipolar protection directly acts without a fault pole selection sub-criterion; if the fault pole selection sub-criterion is met, a fault pole protection action is performed after the fault pole is determined; if the number is determined to be an abnormal large number, locking protection is performed directly; and the direct-current line rapid protection method and system can quickly and reliably identify the faults inside and outside the area, havehigh sensitivity to high-resistance grounding faults, are suitable for LCC and VSC systems, and meet the requirements of multiple aspects.