Abstract: To address the challenges of iron phase enrichment, rapid cycle performance degradation, and the difficulty in balancing stability with low cost of Fe-Al oxygen carriers （OCs） during sludge chemical looping gasification, this study proposes the use of synergistic effects between iron-rich sludge ash （IRSA） and Fe-Al OCs to enhance their oxygen-carrying capacity and cycle stability. Through six consecutive cycles of sludge gasification and OCs regeneration experiments conducted in a bubbling fluidized bed reactor system, the performance differences among three types of OCs—Fe-Al OC, IRSA, and their equal-proportion mixture （Fe1Ash1）—were compared and analyzed, with a focus on their effects on syngas composition and quality, the phase structure and microstructural evolution of the OCs themselves, and carbon deposition behavior. The experimental results indicate that Fe1Ash1 exhibits the optimal catalytic sludge gasification performance. The corresponding syngas calorific value remains stable within the relatively high range of 16 ~ 19 MJ/m³, while the volume fraction of CO₂ in the syngas is significantly reduced, and the selectivity of H₂ and CO is enhanced. This demonstrates that Fe1Ash1 possesses better catalytic function and reaction path selectivity in promoting partial oxidation and hydrocarbon reforming reactions of sludge. XRD and SEM analyses reveal that the addition of IRSA effectively suppresses the migration and agglomeration of Fe species and the formation of Fe₂C, thereby mitigating the sintering phenomenon of the OC. BET test results show that Fe1Ash1 retains a relatively abundant pore structure after multiple cycles, providing a favorable foundation for reaction mass transfer. Furthermore, the post-gasification sludge residue still exhibits a certain oxygen-releasing capacity, confirming the "self-renewal" potential of the OC during the sludge gasification process. This study provides experimental evidence and mechanistic support for the development of low-cost and renewable OCs in the chemical looping gasification of iron-rich sludge, offering valuable insights for promoting the resource-oriented and low-carbon treatment of sludge and the engineering application of chemical looping gasification technology.