Example radio frequency front ends, terminal devices, and carrier aggregation methods are provided. In one example, the radio frequency front end includes: P transmit branches, each transmit branch includes at least one transmit filter, N receive branches, where each receive branch includes at least one receive filter, and a switch circuit having L input ports and at least one output port, where the at least one output port is connected to an antenna or a back end circuit of an antenna, and where the L input ports are used to simultaneously connect a transmit branch of the P transmit branches and a receive branch of the N receive branches, where the transmit branch and the receive branch are corresponding to a same frequency band.