A method for realizing automatic-regulation of voice volume in access gateway includes distributing VOIP voice coding-decoding circuit resource for calling user by access gateway when to send ringing sound to calling user is informed by SS/MGC to access gateway, setting relevant default voice gain value for said coding-decoding circuit according to volume configuration data of calling user, obtaining current voice volume value periodically at conversation time and controlling said coding-decoding circuit to regulate voice gain value according to comparison result of current volume data with configured volume data.