A cloud-based API metadata management method and system. The cloud-based API metadata management method includes the step of installing an API tool by loading the API tool stored in a database by an API tool installation unit of a cloud server, the step of defining a standard API by the API tool installation unit of the cloud server, and creating an API for each hospital server by an API creation unit, and the step of testing the created API for each hospital server by a test unit of the cloud server, correcting data if there is error data, and storing and distributing the data and API for each hospital server if there is no error data.