The utility model relates to a power transmission line fault current precise sampling device, which consists of three normal passages, three fault passages, a peripheral clock control module and a communication module through connection, wherein each passage sequentially has the signal trends from a current preposition processing module, a signal modulation module, an analog-to-digital conversion module, a passage switching module, a data processing module and a data storage module. Through the signal collection passage conversion, current signals in different states are collected in a targeted way, the frequency spectrum range of the collection signals is expanded, the distortion of the high-frequency transient state fault current signals is avoided, and the complete collection of the industrial frequency fault current information is realized.