Abstract: With the continuous expansion of the scale and number of earth-rock dams in China, challenges related to deformation control and structural safety have become increasingly prominent. Accurate monitoring data provide a direct and reliable means of capturing the actual deformation behavior of dams. Compared with deformation measurements at individual monitoring points, full-plane deformation across a characteristic plane of the dam offers a more comprehensive understanding of its structural response, encompassing both local and global deformation trends. To enhance the reliability of deformation and crack analysis for high core rockfill dams (HCRDs), it is necessary to construct a detailed full-plane deformation model of the dam crest. Using the HCRD at Pubugou as a case study, this paper proposes a methodology for constructing and analyzing full-plane deformation at the dam crest based on multi-point monitoring data and statistical analysis. Settlement data from each monitoring point along the dam crest are first processed using a sectional statistical analysis method to establish individual settlement models. This approach enables temporal variations in settlement at different sections of the crest to be effectively captured, providing a foundation for subsequent spatial modeling. Finally, the relationship between the parameters of each settlement model and their corresponding spatial coordinates is examined to construct a statistical model representing the overall settlement of the entire dam crest plane. By integrating data from all monitoring points, the model can estimate full-plane deformation at different time intervals, providing a comprehensive representation of the dam’s deformation process. This method bridges the gap between localized point measurements and the global deformation pattern, enabling more accurate assessment of structural behavior. To further quantify deformation characteristics, the gradient of the full-plane settlement model is calculated to derive the deformation inclination of the dam crest. This facilitates identification and analysis of areas prone to differential settlement or excessive tilting, which are closely linked to crack formation and potential structural risks. The results demonstrate that the proposed methodology constructs a reliable full-plane deformation model of the dam crest. The predicted deformation and crack distributions show good agreement with field observations, confirming the effectiveness and applicability of the approach. By extending deformation analysis from individual monitoring points to a comprehensive characteristic plane, this study enhances the utilization of monitoring data and improves the interpretability of dam deformation patterns. The methodology provides a quantitative and spatially continuous basis for assessing both settlement and crack development, which is critical for structural safety evaluation, maintenance planning, and early warning systems. Moreover, the integration of multi-point data and statistical modeling captures local variations as well as overall trends, facilitating informed decision-making in dam operation and risk management. In conclusion, the approach presented in this paper enables detailed and accurate characterization of full-plane deformation in high core rockfill dams. By combining multi-point statistical analysis with spatial modeling, it offers an effective and reliable tool for monitoring, predicting, and analyzing dam deformation and associated crack development. The method is generalizable and applicable to other large-scale embankment dams, providing a solid foundation for engineering evaluation, operational optimization, and safety management. Overall, this study advances the analytical framework for earth-rock dam deformation, improves monitoring efficiency, and supports the sustainable and safe operation of such infrastructure.