The invention provides an looped network protecting method, a transmission node and a main node, the main node is provided with a timer, the transmission node which detects looped network faults and sends the faults to the main node, the main node sends looped network refreshing message after the main node receives looped network fault message, and meanwhile the timer is started, if the main node does not receive response message in predetermined time, and then looped network refreshing message is sent again, wherein, the response message is sent to the main node after the transmission node which detects looped network faults receives the looped network refreshing message. The method, the transmission node and the main node prevent the looped network refreshing message from loosing in the process of transmitting, avoid serious results such as obstructed looped network link circuit, interrupted business and the like which are caused by the lost of the looped network refreshing message.