It is vital to promote the comprehensive utilization of straw for enhancing the ability of agriculture and rural areas to reduce carbon emissions and fix carbon. Based on the IPCC Guidelines (2006) greenhouse gas (GHG) emission accounting theoretical framework, and in view of the problems of unclear base and unclear bases of GHG emission factors in the comprehensive utilization of straw, an evaluation method for the comprehensive utilization of straw was constructed, the scope and boundary of the evaluation was clarified, the GHG emission factors were scientifically calculated and the carbon-reduction base of different straw utilization technologies were evaluated. Based on different scenarios, the emission reduction and carbon sequestration potential of comprehensive utilization of straw by 2030 and 2060 was predicted. The results showed that the GHG emission reduction contribution of comprehensive utilization of straw in 2020 was 70 million tCO2e. Among them, the GHG emission from open burning and natural decomposition was 5.6×107tCO2e, and the GHG emission reduction from comprehensive utilization of straw was 1.26×108tCO2e. The emission reduction of straw fertilizer and energy utilization were the highest, with emission reduction of 7.9×107tCO2e and 3.8×107tCO2e, respectively. It was estimated that the GHG emission reduction and carbon sequestration contribution potential of comprehensive utilization of straw by 2030 and 2060 would be 1.52×108~1.72×108tCO2e and 2.20×108~2.73×108tCO2e, respectively. The contribution of straw fertilizer to emission reduction in comprehensive utilization was the highest and continued to increase steadily, and it was estimated that the contribution to emission reduction in 2030 and 2060 would account for 40.7% and 31.9%, respectively. Straw energy utilization had the greatest emission reduction potential, and it was estimated that the contribution to emission reduction in 2030 and 2060 would be 55.2% and 62.8%, respectively. Therefore, the dual carbon reduction effects of soil/forest carbon sinks and fossil energy substitution should be paid attention in comprehensive utilization of straw. Adhere to the principle of agriculture-oriented and diversified utilization, increasing efforts to promote full-scale utilization, reducing GHG emissions from incineration, and making full use of straw in reducing carbon emissions, can provide support for achieving the goal of carbon neutrality.