This study examined the catalytic pyrolysis of kraft lignin using an in-situ generated Fe-based catalyst from iron ore. The fresh and spent catalysts were characterized by a transmission electron microscope to investigate the morphological changes of the catalysts. To evaluate the catalysts′ performance, a segmented pyrolysis reactor coupled with time-of-flight mass spectrometry was employed. The results showed that the fresh catalysts had a particle-like morphology, while the spent catalysts appeared sintered. Compared to unreduced iron ore and commercial Fe_2O_3, reduced iron ore significantly promoted the production of monocyclic aromatic hydrocarbons. A yield of monocyclic aromatic hydrocarbons reached 81% at the optimized reaction temperature of 550 ℃, with benzene, toluene, xylene and trimethylbenzene accounting for 46%, 34%, 13% and 7% respectively. Moreover, the possible pathway for kraft lignin via catalytic pyrolysis was proposed based on dehydroxylation and demethoxylation. This work suggests that a low-cost iron ore catalyst could potentially be applied to pyrolyze kraft lignin to produce valuable bio-based aromatic hydrocarbons.