The invention relates to a GNSS-based real-time deformation monitoring system, including a data monitoring, calibration, storage, and distribution processing center, a deformation monitoring data processing module, a real-time dynamic filtering centimeter-level deformation early warning module, and a near real-time two-way filtering/overall adjustment sub- Centimeter-level deformation early warning module, precise post-processing + time series analysis millimeter-level deformation analysis and prediction module. Real-time, near-real-time, post-processing, deformation warning and prediction with step-by-step improvement in accuracy, proposed a fusion scheme of various baseline filtering and adjustment methods, so that the accuracy is improved step by step, real-time warning of centimeter-level deformation, and millimeter-level Time-lapse update of displacement and prediction of deformation trend.