Not only does China possess more than half of the total number of concrete face rockfill dams (CFRD) worldwide, but it has also experienced painful lessons regarding seepage stability control. Particularly, the continuous advancement of digital twin technology within the water conservancy industry offers diverse possibilities for emerging technologies to address traditional engineering difficulties. Against this backdrop, in combination with the engineering practice of Kaihua Reservoir, this paper creatively proposes a “four-preparation” method for the seepage safety of CFRDs based on the building information modeling+ (BIM+) algorithm model. Specifically, to begin with, this research constructs the BIM model applicable to the dam body and foundation in the design stage. Meanwhile, by integrating various information such as material parameters, this research further extracts the calculated cross-section from the model for the finite element seepage stability calculation and slice-method-based dam slope stability analysis, thereby improving the efficiency of design safety calculation. Furthermore, during the operation and management stage, by virtue of diverse technologies such as BIM, GIS, and IoT, this research implements the integration of security monitoring data with digital scenarios. In this foundation, this research establishes a confidence interval statistical model and corresponding graded warning indices through reorganization and analysis, thus forming a technical framework with algorithms for prediction, indices for pre-warning, scenarios for preview, and templates for pre-arranged planning, which furnishes support for engineering safety management.