Abstract: At present, the definition and judgement criteria of key equipment for urban rail transit operation companies are not clear, and there is no unified judgement method. Based on the characteristics of urban rail transit equipment management, definition of key equipment for urban rail transit is proposed. By analyzing key factors in recognizing key equipment, 7 judgement indicators are proposed, including failure rate, purchase price, casualty number, service intermitting time, environment influencing level, equipment maintenance complex coefficient and equipment failure impact range, and the management threshold for 3 indicators are listed, including failure rate, casualty number and service intermitting time. Beijing rail transit signaling profession is taken as example to expound the key equipment judging process.