The present invention relates to a method for obtaining group information by an invited user in a Push-to-Talk over Cellular (PoC) session. The method comprises: sending, by a PoC client where a user initiating the session is located, a session request message carrying information about the user initiating the session and the session group member information to a PoC server; and sending, by the PoC server, the session request message carrying the information about the user initiating the session to a PoC client where the invited user is located. The PoC server sends session group member information to the PoC client where the invited user is located, so that the invited user is able to know the session group member, or refer to the session group member information to determine subsequent operations. The present invention has also disclosed a PoC system.