The present invention relates to an online diagnostic platform, and a permission management method and a permission management system thereof. The permission management method includes: when user information of a registered user is received, assigning a role in a role set to the registered user; determining a permission corresponding to the role; and generating a menu corresponding to the registered user, where the menu includes one or more function portals, the function portal being used for requesting execution of a diagnostic service function. The method uses security control policies such as the registered user, the role and the permission, and is flexible in management and relationship configuration. In addition, the permission management system is separated from a service system, has good expansibility, and can ensure stable running and data security of the system.