Abstract: Accurate measurement of high-current generators in the field of rail transit sensing technology is of great significance for improving the production processes and operational efficiency of rail transit equipment manufacturing. Based on optical fiber sensing methods for detecting high DC currents, this study conducted on-site in-situ calibration tests of the SDDL-3000 A/8 V-type high-current generator at a 3 kA level using a broadband high-current optical fiber measurement instrument. Two sets of repeated and independent high-current measurements were completed, with errors within ±1.5%, providing a solid technical safeguard for rail transit equipment manufacturers to monitor production efficiency and achieve high-quality development.