Using deformation survey data to establish monitoring models is a important way to forecast deformation regulation in slope safety monitoring. To the deformation that has a long period development, there are different regulations between new and old information. Its necessary to use new information correctly to understand slope condition in time and to forecast deformation in the next period. This paper strengthens the importance of new information by giving weight. After selecting the weight function, the weighted regression models and weighted Grey Models of slope deformation have been established. Their forecast results are better than those obtianed by non － weighted models. In addition, several models have been established considering different weights. The corresponding rules and advices have been presented.