A deep eutectic solvent with strong Bronsted acidity was prepared easily by choline chloride and trifluoromethanesulfonic acid. The obtained [ChCl][TfOH](2) catalyst which was characterized by FT-IR, H-1 NMR and TG, possessed greatly enhanced stability than trifluoromethanesulfonic acid, and exhibited excellent catalytic performance in benzylation with benzyl alcohol. Especially, the prepared [ChCl][TfOH](2) catalyst could dissolve into the reactants to realize homogeneous catalysis, and then self-separate from the organic phase after reaction due to the entire consumption of benzyl alcohol. As a result, the catalyst could be recovered and reused simply for six-runs without noticeable loss of catalytic performance. [GRAPHICS] .