As an important part of the power industry, carbon reduction technology in substations plays a key role in supporting the implementation of national policy of carbon peak and reduction. In recent years, a series of carbon emission reduction measures have been developed in the operation phase of substations and promoted beneficial carbon emission reduction. This article summarizes the progress of related technologies and applications from the aspects of substation composition, carbon emission sources, carbon emission reduction technologies, and their effects. Firstly, the composition of carbon emissions from substations during operation is described. Secondly, various measures for carbon emission reduction are reviewed, including the selection of substation equipment types, the intelligent management of substation equipment, and the use of renewable energy. Finally, future technological directions for carbon reduction in substations are discussed, providing technical references and guidance for the sustainable construction and development of low-carbon substations.