Loess tunnel has the problems of shallow buried, large deformation during excavation and poor stability. When the loess tunnel passes through the existing buildings, it will bring great influences on the safety of the surface buildings, it’s in urgent need to ensure that the deformation in the excavation process chanegs within the scope specified in the specification. The deformation law of vault and ground surface in the process of high-speed railway tunnel excavation in clay loess stratum are analyzed. Combined with the analysis of field measured data, it is concluded that the settlement of tunnel in clay loess stratum is directly related to the buried depth and excavation method. There is a significant linear relationship between the surface settlement and the arch crown settlement under the same buried depth, and the ratio has little correlation with the construction method. The deformation control datum of high-speed railway tunnel construction in clay loess stratum is obtained based on the requirements of surface settlement control: Sv = [δ]/i_H. It can be used as a reference for deformation control of similar projects.