Research conclusions ： By doing the numerical calculation，the analyses of the stress change regulation and the influence of the slope shape on the loess slope stability were made to monitor the displacement variation characteristics of the empty surface and internal parts of the slope body. The result showed ： (1) The upright side wall was harmful to the slope stability, and the maximum displacement appeared on the top of the upright side wall. (2) The overall stability of the slope with the upright sidewall is not only affected by the slope of the excavation depth，but also by the slope ratio of the secondary slope adjacent to upright sidewall. When the slope excavation depths were the same, the small the slope ratio of secondary slope was and the better the overall stability of the excavation slope was. (3) To ensure the excavation safety of the temporary loess slope in the open cut exit of the Hanguguan Tunnel of the Zhengzhou – Xi′ an High — speed Railway, the straight slope was used, with the upright sidewall height of 9 m and the secondary slope ratio of 1 : 1. The research results can provide the scientific basis for the similar works.