The present invention relates to a method for one-pot synthesis of ionic liquid with fluoroalkyl group, more particularly to a method for one-pot synthesis of ionic liquid with fluoroalkyl group represented by the following Chemical Formula 1 by adding and reacting a nitrogen-containing compound, a Brønsted acid of the formula YH and a fluoroolefin compound of the formula CFR1═CR2R3 in a single reactor: wherein represents a nitrogen-containing compound; Y− represents an anion of the Brønsted acid; and R1, R2 and R3, which may be same or different, represent hydrogen, fluorine, C1-C10 alkyl or C1-C10 fluoroalkyl having from 1 to 23 fluorine atoms.