Instant messaging achieving method and device

The invention discloses an instant messaging achieving method and device. The method includes determining the transmission network type of interacted message data packages when detecting instant messaging message interaction; conducting format processing on the interacted data packages according to the preset data format if the network is a local area network; transmitting the interacted message data packages subjected to format processing to target users through the local area network or displaying the interacted message data packages subjected to format processing in an instant messaging application. By means of the method and device, a function of instant messaging can be achieved in the local area network on the basis of achievement of the existing instant messaging application, quick interaction between the users of the instant messaging application of the local area network is facilitated, external bandwidth resources are saved to some extent, and bandwidth pressure is reduced.