Abstract: Introduction Under construction in 220 kV Huayue line submarine tunnel project, some emergency danger occurred because of seawater inflow. Method The advantage of freshwater freezing technology had been tried to solve this problem. After several tests of the seawater and soil sample, some calculations were done according to the test data and freshwater freezing theory. Result The problem has been resolved successfully by seawater freezing. The seawater freezing technology has been used for the first time in the nation. Due to this method, the construction can be continuously done according to existing plan, otherwise this tunnel may have to scrap. Conclusion The seawater freezing technology is very efficient and economic to deal with seawater inflow of tuneling under seawater.