For the characteristics of metro arch pressure balance (EPB) shield tunnel construction,first of all,the EPB shield tunnel is analyzed in detail,and their causes,impacts and mitigation measures are also studied accordingly.Then 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.The case history of risk control for EPB shield tunnel in Changsha confirmed the rationality and feasibility of the suggested risk control measures.