The present invention relates to the field of wireless communications technologies, and provides a method for transmitting a carrier, a base station, user equipment, and a system. The method discloses: sending, by a base station, a second carrier, where the second carrier at least partially shares a same resource area with a first carrier, the resource area includes a plurality of resource elements, and the first carrier and the second carrier occupy different resource elements; and sending, by the base station, blank resource element indication information to user equipment that receives the second carrier, where the blank resource element indication information is used to indicate a position of a resource element occupied by the first carrier in the shared resource area. According to the solutions provided in the embodiments, a resource utilization rate of a communications system is improved, and interference between carriers is avoided.