The invention discloses a novel analytical method of deformation monitoring data of a dam slope. Dam slope displacement and a factor influencing the dam slope displacement are monitored, monitoring data are selected, a regression analysis based on proper orthogonal decomposition is carried out to obtain a feature orthogonal basis of proper orthogonal decomposition; quantile regression analyses are carried out on the feature orthogonal basis and the damp slope displacement to obtain regression equation parameters of all quantiles, and then original data substitution is carried out to obtain a quantile regression equation of the original data; and then changing situations of regression equation estimation values of independent variables under different quantiles as well as whether the regression equation estimation values pass the significance test successfully are analyzed and the influence degrees on the dam slope displacement by the independent variables are determined. According to the invention, the method has the great significance in early-warning model establishment for a slope of a dam, slope prediction and forecasting method providing, and slope sensitive influence factor analyses.