Embodiments provide a method for resource allocation, a terminal and a base station are disclosed. In an embodiment the method includes receiving, by a terminal, resource allocation information from a base station, wherein the terminal supports a new system carrier, wherein the new system carrier comprises a component carrier and an extension carrier, and wherein the resource allocation information comprises a resource allocation type and indication information of a first resource block unit and determining, by the terminal, according to the resource allocation information and a mapping relationship between a resource block unit and a physical resource, a first physical resource corresponding to the first resource block unit, wherein the mapping relationship between the resource block unit and the physical resource comprises a first mapping relationship and a second mapping relationship.