Potential limiting device of rail and current drainage cabinet has been used all over the country in the running of the subway, observing the running subway, the rail voltage always keep high value, which leads to rail potential limiting device to keep the closing state, the stray current leakage increased obviously, the current drainage cabinet need to put into use, and when the drainage counter input exhaust flow, will cause the rail potential rise. Therefore, more effective optimization control of rail potential limiting device and current drainage cabinet, can effectively reduce the rail potential, decrease the effect of stray current. This paper will analyze change of rail potential and stray current two traction substation of two rail potential limiting device of multi interval and input current drainage cabinet with no conditions, optimization of rail potential limiting device use method and with the current drainage cabinet.