Abstract: To overcome the problem of insufficient consideration of information dynamics in the traditional connection number method for regional water resources security evaluation,the first-order partial connection number method is introduced,and the dynamic evolution between the identity,discrepancy and contrary components is taken into account to construct the partial triangle of the connection number,and then a new distance measure of the connection number was proposed with the help of the geometric center of gravity model.Considering the impacts of water resources,ecological environment and social economy on regional water resources security,an empirical study on water resources security evaluation in the Beijing-Tianjin-Hebei region based on the new distance measure of the connection number was carried out by using 12 indicators such as population density,the percentage of the affected area and the sewage treatment rate,etc.The results show that:between 2006 and 2020,the water resources security in the Beijing-Tianjin-Hebei region was between safe relatively unsafe,with significant fluctuations.The situation of water resources security is still severe,but it shows a year-on-year improvement trend in general;the water resources situation in Beijing is better than that in Hebei and Tianjin,with Tianjin facing the most severe water resources security situation.The regional water resources security evaluation method based on the new distance measure of connection number is characterized by good conceptual interpretation,and accurate and reliable evaluation results,and provides a new way for the rational water resources security evaluating problems.