Abstract: Through detailed studies on 114 serious urban rail transit operation accidents both in China and abroad, 4 main risk factors in rail transit are summarized as human factors, equipment factors, nature factors, and management factors. Based on the N-K model，the risk probability and coupling value of one-factor coupling, two-factor coupling, and multi-factor coupling are calculated, aiming to obtain the influencing degrees of various risk factors and the coupling modes on the operation of urban rail transit system.