In order to quantitatively identify regional water resources carrying status and its obstacle factors, and to fully mine the micro-uncertainty between evaluation sample and grade criteria, this study proposed a calculation method of dynamic difference degree coefficient that continuously varied with the actual sample value. Then an evaluation and diagnosis model of regional water resources carrying capacity (WRCC) using connection number value was established, and an empirical study was carried out in Anhui Province. The results showed that the connection number value of WRCC in Anhui Province gradually increased from -0.171 in 2011 to 0.067 in 2018, indicating that although the water resources carrying situation in Anhui Province was still quite severe in recent years, the status of each city had been all improved, and the trend after 2013 was more significant. In addition, the average connection number values from 2011 to 2018 in Northern Anhui, Central Anhui, and Southern Anhui were -0.235,0.071, and 0.114, respectively. It reflected that the water resources carrying situations in different regions of Anhui Province were markedly different, presenting a spatial distribution that the carrying situation of Southern Anhui was superior to that of Central Anhui, while the carrying situation of Northern Anhui was weak. Supplementing water resources amount, improving vegetation coverage, controlling water resources exploitation, increasing ecological water supply, and developing water-saving irrigation were effective means to improve the water resources carrying situation in Anhui Province. The application results of regional WRCC evaluation and diagnosis model based on dynamic difference degree coefficient are reasonable, which provides decision support for guaranteeing regional water security.