The disclosure provides a method for bandwidth assignment of an Optical Burst Ring (OBRing), which includes that: a master node acquires current bandwidth resources, and excludes bandwidth resources occupied by over-the-master-node connections from the current bandwidth resources to obtain bandwidth resources to be assigned; and the master node assigns the bandwidth resources to be assigned to each node according to bandwidth requests of each node in the OBRing. The disclosure also provides a device for bandwidth assignment of an OBRing. According to embodiments of the disclosure, the bandwidth resources occupied by the over-the-master-node connections are excluded before bandwidth assignment is started, so that the problem of receiving conflict caused by an over-the-master-node service data connection is solved.