Background: The COVID-19 outbreak has accelerated the huge difference between medical care and disease prevention in Chinese medical institutions. This study aimed to investigate the relationship between the symbiotic units, environments, models, and effects of the integration of medical care and disease prevention. Methods: This cross-sectional study involved 762 employees of public hospitals in 11 cities in Zhejiang Province by random stratified sampling. We analyzed the influence paths of elements in the mechanism of integration of medical care and disease prevention and the mediating effect of symbiotic models among symbiotic units, symbiotic environments, and effects on this integration. Results: The path coefficient of the symbiotic unit on the symbiosis model was 0.46 (p < 0.001), the path coefficient of the symbiotic environment on the symbiosis model was 0.52 (p < 0.001). The path coefficient of the symbiotic unit and the environment was 0.91 (p < 0.001). The symbiotic models exhibited a partial mediation effect between symbiotic units and the effect of this integration. Sobel test = 3.27, β = 0.152, and the mediating effect accounted for 34.6%. Conclusions: It is suggested that health policymakers and public hospital managers should provide sufficient symbiotic units, establish collaborative symbiotic models, and improve the effects of integration of medical care and disease prevention in public hospitals.