Abstract: Tangshan Research Institute,China Coal Technology & Engineering Group，Tangshan 063000，China A large number of cracks appear after the coal resources are mined out according to the design of protective coal pillar under Houxi railway in Wangcun coal mine，leading to subsidence and crack in local sections of Houxi railway roadbed.This affects the stability of roadbed and the stable operation of the train.In order to make sure the design of protective coal pillar under railway more scientific and reasonable，the reasons for cracks are analyzed.Due to the special geological conditions，including the small depth，thin bedrock，less plastic of Quaternary loess layer，and the failure of coal pillars resulted from the mining of 13506 working face to reach full-scale mining，the surface movement and deformation increased，and surface cracks are well developed.According to the analysis，the proactive coal pillar will be re-planned.

Key words: Loess layer, Surface crack, Coal mining under railway, Coal pillar design