The invention belongs to the technical field of chemical synthesis and particularly relates to a preparation method of 4,5-dicyan base-2-trifluoro-methylimidazole and a prepared intermediate and salt thereof. Diaminoaleo dinitrile and trifluoroacetic acid ester are subjected to aminolysis of ester with solvent or without solvent, amide is obtained, the amide is then subjected to intramolecular dehydration, a crude product of the 4,5-dicyan base-2-trifluoro-methylimidazole is obtained, after the crude product is purified, high-purity dehydrate of the 4,5-dicyan base-2-trifluoro-methylimidazole is obtained, then the high-purity dehydrate is mixed with water phase suspension liquid of salt of metal elements and stirred for a reaction, after the reaction is ended, filtering is conducted to remove an undissolved substance, filtrate is evaporated to be dry in a rotary evaporation mode, after dissolution with solvent is conducted again, filtering, rotary evaporation and vacuum drying are conducted, and the high-purity 4,5-dicyan base-2-trifluoro-methylimidazole salt is obtained. The condition of the whole technological process is safer and milder compared with those of other processes for producing the 4,5-dicyan base-2-trifluoro-methylimidazole, and the preparation method meets the requirement for scaled production.