Abstract: With the development of urbanization, garden waste and kitchen waste have become important components of urban solid waste, and there is an urgent need for resource management. This study investigated the effect of kitchen waste as an auxiliary material on the maturity of garden waste composting process. The results showed that the combined composting of garden waste and kitchen waste has achieved mature results, and the combined composting effect was better than the separate composting of garden waste. Meanwhile, compared to separately composting garden waste, co-composting garden waste and kitchen waste could effectively increase GI by 34%. The physical and chemical properties of the final composting product met the national fertilizer standards. This study provided technical reference for the co-composting utilization of garden waste and kitchen waste.