The current emergency power supply measures are not perfect and standardized in response to large-scale power failures, such as city-wide ones. This review paper focuses on reasonably using the emergency electric power source to supply power in case of an abnormal urban power grid, to ensure the regular operation of urban electrical equipment and the daily life of the people. This study first introduces the differ-ent kinds of main emergency electric power sources and analyzes their advantages and disadvantages. The battery of an electric vehicle as a new potential emergency power source is introduced that can also avoid the loss caused by unexpected power failure. Finally, three different emergency power supply methods are explained in detail for different emergency occasions. Among them, the energy router is reviewed com-prehensively considering it is the most potential emergency power distribution approach in the future because of its various applications.