A method for detecting a state of a border gateway protocol, BGP, session, wherein the method is applied to a first network device, the first network device and a second network device have a BGP neighbor relationship, and the method comprises the steps of: creating, by the first network device, a seamless bidirectional forwarding detection SBFD session, wherein the SBFD session is an SBFD session corresponding to a BGP session between the first network device and the second network device, the first network device is an initiator of the SBFD session, the second network device is a reflector of the SBFD session, and the BGP session is a session created based on the BGP neighbor relationship; sending, by the first network device, an SBFD packet to the second network device based on the SBFD session; and determining, by the first network device, a state of the BGP session based on a state of feedback by the second network device for the SBFD packet, wherein a remaining processing capability of the first network device is not lower than a remaining processing capability of the second network device, and wherein the method further comprises the steps of: receiving, by the first network device, a configuration parameter that is of the SBFD session and that is statically configured for the BGP session; or obtaining, by the first network device, neighbor information of the BGP session that is dynamically created, wherein the neighbor information comprises a configuration parameter of the SBFD session, and the configuration parameter is a parameter used by the first network device to create the SBFD session; and the creating, by the first network device, an SBFD session comprises: creating, by the first network device, the SBFD session based on the configuration parameter. creating, by the first network device, a seamless bidirectional forwarding detection SBFD session, wherein the SBFD session is an SBFD session corresponding to a BGP session between the first network device and the second network device, the first network device is an initiator of the SBFD session, the second network device is a reflector of the SBFD session, and the BGP session is a session created based on the BGP neighbor relationship; sending, by the first network device, an SBFD packet to the second network device based on the SBFD session; and determining, by the first network device, a state of the BGP session based on a state of feedback by the second network device for the SBFD packet, wherein a remaining processing capability of the first network device is not lower than a remaining processing capability of the second network device, and wherein the method further comprises the steps of: receiving, by the first network device, a configuration parameter that is of the SBFD session and that is statically configured for the BGP session; or obtaining, by the first network device, neighbor information of the BGP session that is dynamically created, wherein the neighbor information comprises a configuration parameter of the SBFD session, and the configuration parameter is a parameter used by the first network device to create the SBFD session; and the creating, by the first network device, an SBFD session comprises: creating, by the first network device, the SBFD session based on the configuration parameter.