Medical-prevention coordination is an effective way to protect human health throughout the life cycle and deal with infectious diseases. County medical alliance is an important carrier for the construction of primary medical and health service system. How to focus on the grass-roots level and explore and optimize the collaborative path of medical prevention under the new situation has become the focus of medical reform. This paper elaborates on the dilemmas and key issues in the construction of the medical and prevention coordination of the county medical and health service system in China, with the help of the analysis framework of symbiosis theory, and analyzes the symbiosis elements of medical-prevention coordination in county medical alliance from the aspects of symbiosis unit, symbiosis matrix, symbiosis environment and symbiosis mode. In addition, strategies and optimal paths were explored to establish the efficient operation of medical-prevention coordination at the common level of county medical alliance in China, such as ensuring the coordinated development of symbiotic units, laying a solid foundation for symbiotic substrates, improving the symbiotic environment of policies and regulations, and creating a mutually beneficial and symmetrical symbiotic mode.