Abstract：For the characteristics of metro earch pressure balance(EPB) shield tunnel construction，first of all，the risk factors of shield tunnel construction by using the idea of system engineering are identified，and its levels are analyzed，and safety assessment index system is structured. Then the weights of indicators and criteria layer are determined by functional theory. Using SCL and LEC to assess items of guide line layer，carrying out risk levels of the target and guide line layer，using fuzzy comprehensive assessment theory to assess risk level of guide line layer to reach the risk level of the target，these are used to form a safety assessment model，which can provide reference for similar projects construction.
