Abstract：The subsea tunnel has complex geology conditions and surrounding environments，so there are many factors that affect the advancing rate，cost，city environment and safety during the subsea tunnel construction and operation. However，risk management theory has rarely been reported on the construction of large-scale subsea tunnel excavated by drill and blasting method. With the background of Dalian Bay subsea tunnel excavated by drill and blasting method，it will focus on the two schemes during the stage of the feasibility of the project，identifying and analyzing the construction risks，evaluating the risks by using the survey from specialists method based on confidence index. The risk assessment is mainly carried on by the four aspects，i.e. the south shore land field tunnel construction，the subsea area tunnel construction，the north shore tunnel construction and the influence of the construction upon the surrounding environments. Based on the results of risk assessment，the risk of recommended scheme is large. Finally，according to the characteristics of the risks，some measures to reduce or control the risk loss are taken，and some conclusions and suggestions are also proposed. It gives some references to the selection of scheme line and construction management in the engineering decision. Simultaneity，the risk management theory to the construction of subsea tunnel should be adopted，which can provide references to the risk assessment of other similar engineering cases.
