Four Fe-containing ionic liquids (ILs) were synthesized by coupling of conventional imidazole ionic liquids [Cxmim]Cl (x = 4, 8, 12, 16) with FeCl3 and were characterized by FT-IR, Raman, ESI–MS and TG. All of the Fe-containing ILs were applied to the conversion of fructose into 5-hydroxymethylfurfural (HMF) in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) subsequently and the result showed that [C16mim]FeCl4 exhibited excellent catalytic performance. Then the different reaction parameters with [C16mim]FeCl4 as catalyst were studied in detail. A 92.8% yield of HMF was obtained with 0.03 g [C16mim]FeCl4 and 0.1 g fructose in 1.0050 g [Bmim]Cl at 80 °C for 40 min in fructose/[Bmim]Cl solution.