Research on public service facility evaluation has mainly focused on spatial accessibility and facility quality from a supply perspective, but has rarely focused on the evaluation of service facilities from a usage perspective. Researchers can observe the service quality, frequency of use, functional connotation, satisfaction level, and other aspects of facilities from the user’s perspective, effectively compensating for the disadvantage of insufficient precision in traditional macro statistical data. This study proposes a new method for evaluating medical facility usage and service quality based on residents’ activity data. We established an evaluation index system from the perspective of residents’ activity by measuring intensity, frequency, and service satisfaction through network grading data and online comments context. Then, we evaluated the supply and demand relationship of medical facilities, identifying the influencing factors of medical satisfaction. We have also proposed specific strategies for sustainable optimization of medical services. The results show that (1) the service attitude (0.024, 0.002**), service efficiency (0.133, 0.001*), and service quality (0.017, 0.001**) of medical institutions are the core factors that affect medical satisfaction, followed by the convenience of residents in accessing medical resources, showing a significant positive correlation (p < 0.01, Total R2 = 0.9061); and (2) the medical service level in Nanjing City is generally balanced, although spatial heterogeneity exists in the Qixia and Jiangning boroughs.