In order to achieve the plug-and-play capability of distribution terminal， an automatic discovery model for the distribution terminal is proposed. Based on an analysis of the plug-and-play communication process， a Discover/Register model is put forward. The distribution automation master station sends Discover command in search of the distribution terminals， which send Register command to the master station. Abstract syntax notation one（ASN.1） is used for encoding and decoding of the Discover/Register command. The user datagram protocol（UDP）and IP network is used for information transmission. The experimental results show that the Discover/Register model can realize the automatic discovery of distribution terminals.