A method for increasing variable optical channel bandwidth, comprising: adding, by a first network node, a timeslot increase indication to an HO ODU frame and sending the HO ODU frame to which the timeslot increase indication is added to a second network node, wherein the timeslot increase indication is used to instruct a timeslot, occupied by an ODUflex bit stream, of the HO ODU frame, starting from a next HO ODU frame of the HO ODU frame, to increase from X timeslots to Y timeslots, X is greater than zero and less than Y, and the second network node is a downstream network node of the first network node in a link through which a service stream flows; starting from the next HO ODU frame of the HO ODU frame to which the timeslot increase indication is added, mapping, by the first network node, a bit stream at a third rate formed by an ODUflex bit stream at a first rate and an idle data bit stream at a second rate to the Y timeslots of the HO ODU frame and sending the HO ODU frame to the second network node, wherein a rate corresponding to the Y timeslots of the HO ODU frame is greater than or equal to the third rate, both the first rate and the second rate are less than the third rate, and the second rate is a difference value between the third rate and the first rate; after each network node in the link receives the HO ODU frame to which the timeslot increase indication is added, mapping, by the first network node, an ODUflex frame to which a rate increase indication is added to the HO ODU frame and sending the HO ODU frame to the second network node, wherein the ODUflex frame to which the rate increase indication is added is an ODUflex frame bearing the ODUflex bit stream, and the rate increase indication is used to instruct a rate of the ODUflex bit stream, starting from a next ODUflex frame of the ODUflex frame to which the rate increase indication is added, to increase from the first rate to the third rate; and starting from the next ODUflex frame of the ODUflex frame to which the rate increase indication is added, mapping, by the first network node, the ODUflex bit stream at the third rate to the Y timeslots of the HO ODU frame and sending the HO ODU frame to the second network node. adding, by a first network node, a timeslot increase indication to an HO ODU frame and sending the HO ODU frame to which the timeslot increase indication is added to a second network node, wherein the timeslot increase indication is used to instruct a timeslot, occupied by an ODUflex bit stream, of the HO ODU frame, starting from a next HO ODU frame of the HO ODU frame, to increase from X timeslots to Y timeslots, X is greater than zero and less than Y, and the second network node is a downstream network node of the first network node in a link through which a service stream flows; starting from the next HO ODU frame of the HO ODU frame to which the timeslot increase indication is added, mapping, by the first network node, a bit stream at a third rate formed by an ODUflex bit stream at a first rate and an idle data bit stream at a second rate to the Y timeslots of the HO ODU frame and sending the HO ODU frame to the second network node, wherein a rate corresponding to the Y timeslots of the HO ODU frame is greater than or equal to the third rate, both the first rate and the second rate are less than the third rate, and the second rate is a difference value between the third rate and the first rate; after each network node in the link receives the HO ODU frame to which the timeslot increase indication is added, mapping, by the first network node, an ODUflex frame to which a rate increase indication is added to the HO ODU frame and sending the HO ODU frame to the second network node, wherein the ODUflex frame to which the rate increase indication is added is an ODUflex frame bearing the ODUflex bit stream, and the rate increase indication is used to instruct a rate of the ODUflex bit stream, starting from a next ODUflex frame of the ODUflex frame to which the rate increase indication is added, to increase from the first rate to the third rate; and starting from the next ODUflex frame of the ODUflex frame to which the rate increase indication is added, mapping, by the first network node, the ODUflex bit stream at the third rate to the Y timeslots of the HO ODU frame and sending the HO ODU frame to the second network node.