In order to describe the temporal and spatial distribution of rail temperature comprehensively

we designed an effective rail cooling system. Moreover

we designed and built a rail temperature measurement system based on fiber Bragg grating（FBG）

and obtained the rail temperature variation. According to the delay temperature data

the rail temperature distribution and evolution were conjectured. Results show that the joule energy of rail resistance is the largest part in the all thermal energy. The rail thermal energy distribution is uneven

while the staring position of the armature possesses the highest thermal energy. The rail thermal energy reaches a balance at the cross-section

and then conducts to the both ends gradually. These conclusions can provide the basis for the verification and correction of simulation model and the design of rail cooling system.