Abstract: This paper focuses on the 6 kV lines in the power distribution network of petrochemical plants, discussing the necessity and application effects of adding optical fiber differential protection. By analyzing the principles, characteristics, and practical applications of optical fiber differential protection in the power distribution network of petrochemical plants, and combining the specific conditions and requirements of petrochemical plants, it selects the appropriate type of optical fiber differential protection device for the lines and conducts calculations and verifications for current transformers, ensuring the practicality and effectiveness of the protection scheme.