While research in multiple countries confirms that primary care functional features significantly improve patient health, China's primary care system differs markedly due to unique structural and contextual factors. This study aims to measure and explore the functional features experienced by patients received family doctor contract service in the past year, evaluating the impacts and pathways of these primary care features on health outcomes. We employed a mixed-methods explanatory sequential design. In the quantitative phase, we randomly selected 2118 residents from 12 primary care institutions. The intensity of functional features was assessed using the Person-Centered Primary Care Measure (PCPCM), and their association with levels of EuroQol Visual Analogue Scale (EQ VAS) was evaluated through multilevel modelling. In the qualitative phase, a qualitative description approach was used, conducting 24 focus groups with a total of 85 patients to gather in-depth information about their experiences with functional features and perceived health impacts. Finally, the quantitative and qualitative data were integrated using meta-synthesis and joint display methods to validate, interpret, and expand the results. The average PCPCM score was 3.65, with subdomain scores ranging from 3.39 to 3.83. Qualitative findings confirmed the quantitative results regarding the intensity and manifestation of features like accessibility, coordination, and relationship-building. However, discrepancies were noted in features such as comprehensiveness, integration, and family and community context. Additionally, two new functional features, 'being appreciated' and 'being cared for,' were identified. The quantitative results also showed that higher PCPCM scores were positively associated with EQ VAS levels (odds ratio (OR) = 1.18; 95% confidence interval (CI) = 1.03-1.35, P < 0.001). Furthermore, qualitative results revealed six key pathways supporting the beneficial effects of local primary care functional features on health maintenance and improvement. This study demonstrates high functional scores for Shanghai's family doctor services and highlights a positive association between primary care functionality and population health. These features and their health benefits are deeply shaped by the local social and health care context. This confirms the progress of Shanghai's primary care development and underscores the need for further exploration of primary care functional features across China, along with the development of tools tailored to local conditions to better measure and improve primary care quality and health outcomes. primary healthcare; primary care; quality measurement; population health; mixed method research; China.

Primary care functional features and their health impact on patients enrolled in the Shanghai family doctor service: a mixed-methods study