Objective Acetate is an important substrate for methane production, and its mineralization and transformation are key to the carbon cycle, carbon sequestration, and greenhouse gas mitigation in paddy soils. In long-term flooded paddy soils, iron, an important valence-variable metal, may influence the mineralization and transformation of acetate.Method Therefore, ¹³C-acetate, ferrihydrite and goethite were added into paddy soil and the CO₂ and CH₄ emissions were monitored. Also, the changes in paddy soil properties during anaerobic incubation (100 days) were analyzed. Additionally, we analyzed the characteristics of mineralization and transformation of acetate and its priming effect on CO₂ and CH₄ to reveal the roles of different types of iron oxides.Result The results showed that in the acetate treatment after incubation, 33% and 36% of acetate was mineralized to CH₄ and CO₂, respectively, while 0.12%, 2% and 28% were transformed to dissolved organic carbon (DOC), microbial biomass carbon (MBC) and soil organic carbon (SOC), respectively. Acetate caused a negative CO₂ priming effect and a positive CH₄ priming effect. The ratio of CO₂ to CH₄ sourced from soil organic carbon was changed from 3.46: 1 to 1.83: 1 by acetate addition. Goethite addition significantly increased acetate derived cumulative CO₂ emission, while ferrihydrite showed no significant effect. Ferrihydrite and goethite significantly decreased SOC derived CO₂ emission and strengthened the negative CO₂ priming effect of acetate. Also, ferrihydrite and goethite significantly decreased acetate derived CH₄ emission and showed no significant effect on SOC derived CH₄ emission. The proportions of acetate transformed to MBC and SOC were significantly increased in the presence of ferrihydrite and goethite.Conclusion The mineralization and transformation of acetate influenced CO₂ and CH₄ emission from native SOC. Ferrihydrite and goethite, different in crystallinity, have different effects on mineralization, transformation and priming effect of acetate. Thus, this study can provide theoretical and technical support for carbon sequestration and greenhouse gas mitigation in paddy soils.