Abstract: To overcome the shortcomings of the TOPSIS method commonly used in water security assessment, which is suitable for ranking but relatively weak in decision-making guidance, this study improve its data standardization by using the relative membership degree method in variable fuzzy sets. Correspondongly the closeness degree is calculated to estimate the conditional probability in three-way decision process and generates decision rules based on the comprehensive thresholds. By setting different risk aversion coefficients σ, the granularity of three-way decision is dynamically refinedt to achieve level assessment and regulatory decision-making. Guided by the concept of resilience, a water security assessment indicator system is constructed from three aspects: resistance, resilience, and adaptability, and a case study is conducted in Beijing-Tianjin-Hebei Region. The results show that from 2006 to 2020, the water security level in the Beijing, Tianjin and Hebei has steadily increased with significant spatial differentiation. Beijing and Tianjin show minimal interannual variation, while Hebei has shown significant improvement since 2015. The main resilience regulation direction for water security in Beijing and Tianjin is resistance, while Hebei needs to further enhance adaptability.