Abstract: The problem of water accumulation in the foundation pit of switch machine commonly exists among metro operation lines. It often causes the installation device of switch machine and the rod body to be immersed in water,which has enormous negative impact on the train operation safety. Since this problem is very difficult to rectify in existing lines,and prevention is easy to achieve in the construction of new lines,practical schemes for the construction of new lines targeting switch machine foundation pit water accumulation such as preventive measures,precautions during construction phase,acceptance testing are proposed.