A method and device for Bidirectional Forwarding Detection under a condition of parameter update, wherein a first router establishes a link with a second router; the first router modifies packet sending parameters and/or packet receiving parameters, and sends to the second router a message with an identifier of the modification of this time; the second router returns to the first router a feedback message with an identifier of the modification of this time after receiving the message with the identifier of the modification of this time sent by the first router; the packet sending parameters and/or packet receiving parameters which are modified this time take effect after the first router receives the feedback message with the identifier sent by the second router.