Online medical services are developing rapidly worldwide, and policies encourage the integrated development of online and offline services in China. However, there is a lack of comprehensive and systematic quality indicators for online medical services to ensure patients' safety. This study aimed to construct a set of quality indicators from the perspective of online-offline integration, to provide a basis for the evaluation and management of online medical service quality. Based on the literature review, we included 53 potential indicators. In two rounds of consultations, we invited 21 and 19 experts, respectively, to rate the importance and feasibility of each indicator via email. We used the modified Delphi method and analytic hierarchy process to determine the final indicators and their weights. We used experts' positive coefficient, authority coefficient, and opinion coordination degree to test the reliability and validity of experts. After two rounds of Delphi consultation, the experts' positive coefficients were 90.48% and 89.47%, and the authoritative coefficients were both over 0.7. An online medical service quality index system for public hospitals in China was developed with 4 primary indicators, 13 secondary indicators, and 34 tertiary indicators. Among the primary indicators, the weights of structure, process, outcome, and integration quality were 0.22, 0.26, 0.34, and 0.18, respectively. We constructed the first set of online medical service quality indicators for public hospitals in China from the perspective of online-offline integration. It could be applied as a standardized and meaningful guide for online medical service evaluation and quality development.