Abstract: In a group chat-based instant messaging method, a message is received from a first messaging application of a first user in a first messaging group. The first messaging application is associated with a first messaging service. When the message is to be announced to all group members of the first messaging group, whether the first user is authorized to send the message is determined based on identity information of the first user. Based on the first user being authorized, protocol conversion on the message is performed based on a second messaging protocol of a second messaging service to output the message in a first preset announcement style for messages announced to all group members. The converted message is transmitted, via a second messaging server, to a second messaging application corresponding to one of the plurality of group members in the first messaging group.