The natural Na-type montmorillonite (Na-MMT) was pillared by iron polycation to obtain Fe-pillared montmorillonite (Fe-MMT). The materials were characterized by X-ray powder diffraction and N2 adsorption–desorption at low temperature. It was found that iron polycation was successfully inserted into MMT layers, and the textural properties of Fe-MMT could be adjusted by altering the amount of iron. Meanwhile, the decolorization of methyl orange (MO) by heterogeneous Fenton-like oxidation using Fe-MMT as catalyst was evaluated. The experimental results showed that Fe-MMT exhibited good decolorization performance of MO under 2.0 g L−1 of Fe-MMT-1.5, initial pH of solution 4, reaction time 90 min, and H2O2 concentration of 5 mmol L−1. Fe-MMT exhibited good stability for the decolorization of MO in solution for three successive runs. The decolorization process could be well described by pseudo firstorder kinetics model. Na-montmorillonite (MMT) pillared by iron polycation (Fe-MMT), an efficient Fenton-like catalyst was developed. The decolorization efficiency of methyl orange (MO) was dependent on the textural properties of Fe-MMT adjusted by altering the amount of iron. Excellent decolorization efficiency of MO (91.6–87.9%) was achieved under the optimal conditions.