The present invention is applicable to the field of communications, and provides a method, an apparatus and a system for establishing a neighbor relation. The method includes: receiving a discovery message sent by a long term evolution element management system LTE EMS for discovering an LTE to 3rd generation mobile communication 3G neighbor relation; obtaining, according to the discovery message, an LTE-3G neighbor relation policy corresponding to the LTE-to-3G neighbor relation among locally stored LTE-3G neighbor relation policies; and establishing a 3G-to-LTE neighbor relation if the policy allows a bidirectional neighbor relation. The technical solutions provided in the present invention have the advantage that a network terminal has few limitations.