The invention provides a bandwidth sharing method and a bandwidth sharing device for a terminal cell based on SDN control. The bandwidth sharing method comprises the following steps: determining, by an SDN controller, whether a bandwidth sharing trigger request is received, wherein when the trigger request indicates the target service of any terminal cell on a processing backhaul link, a shared bandwidth needs to be provided by other terminal cells, and the bandwidth demand of the target service is larger than or equal to a first preset threshold; when receiving the trigger request, selecting any terminal cell to provide at least one terminal cell of the shared bandwidth; and controlling any terminal cell and the at least one terminal cell to process the target service together. By adopting the bandwidth sharing method provided by the invention, the SDN controller can bind the bandwidth resources of a plurality of T-SC on the backhaul link and provide the same to the bandwidth service for use, thereby guaranteeing the application of the wireless backhaul sharing mechanism between T-SC and realizing a technical effect of flexibly configuring the bandwidth resources on the backhaul link.