In the field of optical communications, a method and a device for adjusting transmission of transport network data are provided. The method includes the following steps. Information of adjusting a designated Optical Transport Network (OTN) line sent from an OTN is received. The OTN line corresponding to the information of adjusting the designated OTN line is adjusted. Changed data traffic of the adjusted OTN line is calculated. An Ethernet channel to be adjusted according to the changed data traffic is designated, and the Ethernet channel to be adjusted is adjusted correspondingly. The device includes a Link Capacity Adjustment Scheme (LCAS) module and a channel processing module. According to the method and the device, the adjustment of the OTN line is associated with the adjustment of the Ethernet channel, thereby ensuring the data transmission efficiency, and improving the overall performance of a network.