Abstract: To explore the feasibility of integrating carbon-based and iron-based materials in the anaerobic digestion of hulless barley straw, seven different conductive materials were selected as additives. The effects of varying mixed amounts of carbon-based and iron-based materials on the anaerobic digestion performance of hulless barley straw were assessed. The results demonstrated that the combination of carbon-based and iron-based materials enhanced the degradation rates of cellulose and hemicellulose in the straw. Compared to the treatments with individual addition and no addition of conductive materials (control), the majority of mixed addition treatments demonstrated superior synergistic effects, significantly enhancing the methane production performance of hulless barley straw (P<0.05). Furthermore, there was an optimal combination for the mixture of carbon-based and iron-based materials. Compared to the mixture of graphite with iron-based materials, the combination of activated carbon and biochar with iron-based materials yielded better results. Among them, treatments with 8% activated carbon mixed with iron filings and 8% biochar mixed with Fe₃O₄ achieved a higher cumulative methane production, at 221.52 and 219.47 mL/g, respectively. This represented an increase of 44.34% and 43.00% over the control, and an increase of more than 28.71% and 26.85% compared to their individual additions, respectively. These two treatments also perform better in terms of economic benefits, making them the most suitable carbon-based and iron-based material combinations for the anaerobic digestion of hulless barley straw. Additionally, the use of carbon-based and iron-based materials could effectively prevent environmental pollution caused by chemical treatment of straw, representing an efficient, eco-friendly, and simple method for processing lignocellulosic waste.