A method for bandwidth map update includes: after receiving a bandwidth report carried by a control frame, a master node newly establishing a bandwidth map, newly establishing a resource state table, and setting all resource states in the newly established resource state table to be available; adding a cross-master node transport channel drop allocation structure of the newly established bandwidth map in accordance with a cross-master node transport channel add allocation structure of a bandwidth map to be updated, and updating the resource state table; according to the bandwidth report carried by the control frame, allocating a wavelength and an optical burst timeslot one by one to a current bandwidth request, adding wavelengths and optical burst timeslots to the newly established bandwidth map, generating a new bandwidth map, and updating the resource state table; and distributing the control frame carrying the new bandwidth map to slave nodes hop by hop.