In this paper, taking the Shuping landslide in Zigui County in Three Gorges Reservoir Area as an example, and specifically evading some monitoring points possibly affected by the water level fluctuating of the Yangtze River in Three Gorges reservoir area, we conduct smoothing and equidistance processing of the data by separately using orthogonal polynomials and cubic spline function. And it is based on removal of the data with abnormal changes by using t-test for monitoring data of deformation and rainfall of Shuping landslide. Furthermore, we carry out quantitative analysis of the correlation and summarize the general rule that the landslide deformation is influenced by rainfall. When rainfall reaches a certain threshold, the correlation coefficient between deformation rate and rainfall turns from negative to positive. And the results are given for a number of clear quantitative analysis. It can provide some reference for monitoring and analyzing similar landslides. In this paper, taking the Shuping landslide in Zigui County in Three Gorges Reservoir Area as an example, and specifically evading some monitoring points possibly affected by the water level fluctuating of the Yangtze River in Three Gorges reservoir area, we conduct smoothing and equidistance processing of the data by separately using orthogonal polynomials and cubic spline function. And it is based on removal of the data with abnormal changes by using t-test for monitoring data of deformation and rainfall of Shuping landslide. When the rainfall reaches a certain threshold, the correlation coefficient between deformation rate and rainfall turns from negative to positive. And the results are given for a number of clear quantitative analysis. It can provide some reference for monitoring and analyzing similar landslides.