The present invention relates to a salt of a dioxygenase inhibitor and a preparation method therefor and the use thereof, in particular relates to a salt of (Z)-N-(3-bromo-4-fluoro-phenyl)-4-((2-(N-(cyclopropylsulfonyl)-S-methylsulfinylimine)ethyl)amino)-N' -hydroxy-1, 2, 5-oxadiazole-3-carboxamidine having the structure of general formula (I), a preparation method therefor and the use thereof, and a pharmaceutical composition comprising a therapeutic effective amount of the salt. The salt can be widely used to treat or prevent cancers or tumours, virus infections, depression, neurodegenerative disease, trauma, age-related cataract, organ-graft refection or autoimmune diseases, and is expected to be developed into a new generation of immunosuppressors, wherein the definition of each substituent in the general formula (I) is the same as defined in the description.