The invention relates to the technical field of flame retardants, in particular to a fluorine-containing DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) derivative flame retardant with the structural formula shown in the specification. The preparation method of the fluorine-containing DOPO derivative flame retardant comprises steps as follows: (1) diphenyl phosphoramidate and 3,5-difluoropyridin-5-formaldehyde are heated in a solvent, and a reaction system containing an intermediate product I is obtained after the reaction ends; (2) DOPO is added to the reaction system containing the intermediate product I obtained in the step (1) to be heated, washing and drying are performed after the reaction ends, and the fluorine-containing DOPO derivative flame retardant is obtained. According to the fluorine-containing DOPO derivative flame retardant and the preparation method thereof, with increase of the content of phosphorus in a cured product, the flame retardance of the cured product is improved; when the content of the flame retardant reaches 5%-10%, the cured product can reach the UL-94, V-0 level.