In the process of achieving the "dual carbon" goal, the proportion of electricity in terminal energy consumption will gradually increase, which makes the low-carbon transformation of the power industry a basic prerequisite for carbon reduction and emission reduction in the whole society. The flexible load in power system can reduce carbon emissions during system operation through demand response technology, but existing power demand response technology and low-carbon demand response technology based on dynamic carbon emission factors cannot allow users to intuitively capture the carbon reduction benefits through electricity consumption changing. In response to this issue, a low-carbon demand response technology based on marginal carbon emission factors is proposed. This technology directly uses the marginal carbon emission factors of each node as a guiding signal, which can inform users of the changes in carbon emissions caused by increasing or decreasing electricity consumption in the current state, thereby guiding users to take spontaneous measures to reduce system carbon emissions. In addition, the impact of uncertainty in new energy output on user preference for low-carbon demand response measures is also analyzed, and simulation verification is conducted based on the modified PJM-5 system. The experimental results verify the effectiveness of the proposed method.