Four iron ores including limonite, siderite, hematite and magnetite are examined for their catalytic effects on coal pyrolytic products. Experiments were conducted at a pyrolyzer combined with gas chromatography/mass spectrometry (Py-GC/MS). The results show that limonite has the highest catalytic activity for light aromatic formation as a result of the conversion of aliphatic hydrocarbons and oxygenates. The total peak area of light aromatics such as benzene, toluene, ethylbenzene, xylene, and naphthalene (BTEXN) has increased by 52% after the catalysis of limonite. The good performance of limonite can be attributed to its large surface area. Multi-cycle tests were conducted over limonite to get the knowledge of its stability. The effect of valence state of iron is discussed by making comparison of the performances between the limonite and the reduced limonite. It is found that the reduced limonite has a more reactive catalytic activity for light aromatics production. Coal effect is also studied.