Abstract: Under the unattended train operation mode of urban rail transit, setting Staff Protection Key Switch(SPKS) in the Fully Automatic Operation (FAO) area is an important means to ensure the safety of ground personnel. Taking Taiyuan Rail Transit Line 2 as an example, according to the functional requirements of SPKS and combined with its line conditions, this paper introduced the engineering application scheme of SPKS, including the setting mode of SPKS, the division principle of protection zoning, and the management mode matching the application of SPKS. The scheme has been implemented in Taiyuan Rail Transit Line 2, which protected effectively the safety of on-site personnel and improved the emergency response capacity in emergency scenarios. It can provide reference for the construction of other FAO lines.