Taihangshan tunnel is a passengerdedicated railway tunnel located dominantly in breccia marl of Grade Ⅴ ground (gypsum breccia). By means of monitoring on the tunnel located in the special ground, the mechanisms of the deformation and displacement of the tunnel and the variation rule of the rock mass pressure are obtained to optimize the tunnel construction and the reinforcement parameters. The paper can provide reference for the design and construction of similar works in the future.