The invention discloses a method, a device and a system for managing a GPON branch in a multi-service transmitting network. The method comprises the steps of: converting an uplink OAM message which is required to be processed by a transmitting network main node into an uplink transmitting network control and management message and sending to the transmitting network main node after receiving the uplink OAM message on the GPON branch by a transmitting network node, and converting a downlink transmitting network control and management message configured or inquired by a light network unit into a downlink OAM message and sending to the light network unit after the transmitting network node receiving the downlink transmitting network control and management message sent by the transmitting network main node. By using the invention, the transmitting network main node can uniformly manage the GPON branch.