Abstract: With the extensive application of fully automatic operation (FAO) system in urban rail transit, higher requirements are raised for reliable and flexible train control functions. In FAO system, the responsibilities of train door control are transferred from train driver to train signaling system which provides more control modes for dispatchers. Based on the signal system of Taiyuan rail transit Line 2, the critical function performance of train door control are analyzed from the perspective of operational requirements, including automatic train door opening and closing, application and release of train door inhibition, train door remote control, train door and platform door fault isolation under FAO mode.