The construction of expressways in mountainous areas, with a high fill subgrade construction of deep excavation, is often encountered [1-3]. Combined with the regular pattern of the development of high embankment settlement, the fuzzy combination forecasting method of self-adaptive variable weight is applied to the subgrade settlement of the Changsha Jishou expressway, which provides the prediction accuracy and reliable applicability [4, 5]. Faults in the roadbed settlement are prevented and safe operation is ensured.