Abstract: A terminal device security management device and method are involved a terminal device management field. By grading network level, a level of functions being forbidden to be invoked, formed by obtaining a network connected by the terminal device, is sent to the terminal device for managing invoking operations of the functions. The terminal devices in different management domains are managed based on different connected networks for licensing the terminal device to invoke different function sets in different management domains. Work efficiency is improved, and a risk of leaks is reduced. A terminal device and a method of the terminal device are also disclosed. By responding information of a management device, a licensed function set is displayed in a display, or an invoking of the function is forbidden based on an invoking request for avoiding the specified function to be invoked in the management domain. The leak risk is further reduced.