A method and system for controlling a talk time for a PoC user is provided, capable of freely extending and using the talk time according to whether there is a floor requester or a priority when a talker obtains a floor during PoC communication. The method includes determining whether a talk limit time of a PoC client that is transferring a talk burst is close at hand; when the talk time limit is close at hand, determining whether or not a floor requester who makes a request for a floor is in a floor list for storing the floor requester; and when the floor requester is not in the floor list, extending the talk time and transferring the talk burst.