Abstract: The safety operation of underground railway is seriously affected by water corrosion. The key to solve the problem is correctly evaluating the corrosion of groundwater. Taking Shenzhen Metro Line 11as an example, erosion analysis reports of 627 groundwater samples taken from 30 sections of Metro Line 11 are collected. The whole line of groundwater corrosion intensity distribution is obtained, which is analyzed combined with the seawater intrusion area that passed through by Shenzhen Metro Line 11. The conclusion is the following. For the typical environment of seawater intrusion, there is a closely relationship between the groundwater erosion and the distribution of seawater intrusion, which includes the reclamation area. Discrimination of steel corrosion grade of subway underground structure should be carried out according to the environment of wet and dry cycles. The study provides guidance for the groundwater corrosion evaluation of subway lines in the coastal city with seawater intrusion area.