Stepwise landslide warning surface model is presented based on moving least squares. Based on the monitoring data of the Wangjiapo landslide in Three Gorges Reservoir area, the proposed model is set up, and its ability to provide early warning of the stepwise deformation is validated. The cumulative displacement-monitoring period curve is fitted via moving least squares, and its derivative is used to determine the range of the stepwise deformation during the landslide. The maximum point of its second derivative within the deformation range is taken as the “quasi-failure point” to obtain the current rainfall, previous rainfall, and displacement rate thresholds of each stepwise deformation. The threshold surface of the stepwise deformation is constructed with the monitoring information of the “quasi-failure point” by using moving least squares. A four-level warning threshold surface model is established with the displacement rate as the classification standard for early warning analysis. The validation results of the Wangjiapo landslide show that the warning level is consistent with the actual displacement of the landslide. The model has good early warning effect and enables warning of landslide stepwise deformation.