The present application discloses a link state information advertisement method and device, including: receiving, by a first network device, network topology information sent by a control device, where the network topology information includes link state information, which is generated by the control device, between the first network device and a second network device, the first network device supports an IGP, and the second network device does not support the IGP; and advertising the link state information between the first network device and the second network device. The first network device advertises the link state information to other network devices supporting the IGP, therefore implementing that a network device supporting the IGP in multiple network devices controlled by one control device accesses a network device not supporting the IGP, thereby optimizing routing between multiple network devices controlled by the control device.