In the current national design codes and standards, there are definite provisions for the cuttingoff of the nonfirefighting power supply, however, there are no specific provisions on the purposes, manners (manual cuttingoff manner or automatic cuttingoff manner) and positions of the cuttingoff of the nonfirefighting power supply. In this article, analysis is made on the purposes, manners (manual cuttingoff manner or automatic cuttingoff manner) and positions of the cuttingoff of the nonfirefighting power supply. The main principles and purposes of the cuttingoff of the nonfirefighting power supply in case of fire are defined, i.e., trying to avoid passenger chaos and secondary incident, trying to avoid further spread of the fire, trying to ensure the safety of the firefighters and trying to minimize the power cuttingoff scope. Finally, the principles, manners and positions of the cuttingoff of the nonfirefighting power supply in case of fire occurring in the equipment area and public area of Metro stations are proposed on basis of the features of the power load and operation management of Metro stations.