Abstract: [Purpose/Significance] In the traditional mode of diagnosis and treatment, the primary doctors have little chance to practice diagnosis and treatment and contact the complicated patients, so their service level is difficult to improve. Online Health Communities（OHCs）, as a supplement of offline medical services, provides a new platform for the primary doctors to improve their offline service quality. Therefore, it is necessary to study the impact of online services of primary doctors on their offline medical service quality. [Design/Methodology] Based on the Spillover Effect theory, this study draws on the primary doctors of "Good Doctor Online" as the research participants and constructs a theoretical model to explore how online services（paid-knowledge sharing and free-knowledge sharing） influence offline service quality. [Findings/conclusion] The research findings show that paid-sharing and free-sharing activities inonline health communities can improve the quality of primary doctors' offline services. Both offline title and online reputation of primary doctors positively moderate the relationship between online service and offline service quality. [Originality/Value] Our study enriches the current research on spillover effect in healthcare field and the empowerment of online health communities for primary medical institutions. Combined with the implementation of the hierarchical diagnosis and treatment policy in China, it also provides practical implications for improving the service capabilities of primary medical and health institutions.

Key words: Online health community, Primary doctor, Spillover effect, Health service quality