Straw retention has been shown to reduce carbon dioxide (CO₂) emission from agricultural soils. But it remains a big challenge for models to effectively predict CO₂emission fluxes under different straw retention methods. We used maize season data in the Griffith region, Australia, to test whether the denitrification-decomposition (DNDC) model could simulate annual CO₂emission. We also identified driving factors of CO₂emission by correlation analysis and path analysis. We show that the DNDC model was able to simulate CO₂emission under alternative straw retention scenarios. The correlation coefficients between simulated and observed daily values for treatments of straw burn and straw incorporation were 0.74 and 0.82, respectively, in the straw retention period and 0.72 and 0.83, respectively, in the crop growth period. The results also show that simulated values of annual CO₂emission for straw burn and straw incorporation were 3.45 t C ha⁻¹ y⁻¹and 2.13 t C ha⁻¹ y⁻¹, respectively. In addition the DNDC model was found to be more suitable in simulating CO₂mission fluxes under straw incorporation. Finally the standard multiple regression describing the relationship between CO₂emissions and factors found that soil mean temperature (SMT), daily mean temperature (Tmean), and water-filled pore space (WFPS) were significant.