A downlink transmitting system (300, 400, 500), comprising: at least one digital intermediate frequency module group, at least one transmit, Tx, port group (361, 362, 363, 441, 442, 443), a plurality of power amplifiers, PAs (3311, 3312, 3321, 3322, 3331, 3332, 3333, 3334, 451, 452, 453, 454, 455, 456, 5211, 5212, 5221, 5222, 5231, 5232, 5233, 5234), at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533), and an antenna array (350, 460), wherein the plurality of PAs are connected to the antenna array (350, 460), the plurality of PAs are connected to all Tx ports comprised in the downlink transmitting system (300, 400, 500) in a one-to-one correspondence, the at least one digital intermediate frequency module group is in a one-to-one correspondence with the at least one Tx port group (361, 362, 363, 441, 442, 443), each of the at least one Tx port group (361, 362, 363, 441, 442, 443) is connected to each digital intermediate frequency module in a corresponding digital intermediate frequency module group through one of the at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533), each of the at least one Tx port group (361, 362, 363, 441, 442, 443) comprises a plurality of Tx ports, a quantity of digital intermediate frequency modules comprised in each digital intermediate frequency module group is equal to a quantity of Tx ports comprised in a corresponding Tx port group (361, 362, 363, 441, 442, 443), each of the at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533) comprises at least two connection states, quantities of enabled digital intermediate frequency modules in a digital intermediate frequency module group connected to the each of the at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533) in different connection states are different, and all Tx ports in a Tx port group (361, 362, 363, 441, 442, 443) connected to the each one of the at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533) in the different connection states are in an enabled state. at least one digital intermediate frequency module group, at least one transmit, Tx, port group (361, 362, 363, 441, 442, 443), a plurality of power amplifiers, PAs (3311, 3312, 3321, 3322, 3331, 3332, 3333, 3334, 451, 452, 453, 454, 455, 456, 5211, 5212, 5221, 5222, 5231, 5232, 5233, 5234), at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533), and an antenna array (350, 460), wherein the plurality of PAs are connected to the antenna array (350, 460), the plurality of PAs are connected to all Tx ports comprised in the downlink transmitting system (300, 400, 500) in a one-to-one correspondence, the at least one digital intermediate frequency module group is in a one-to-one correspondence with the at least one Tx port group (361, 362, 363, 441, 442, 443), each of the at least one Tx port group (361, 362, 363, 441, 442, 443) is connected to each digital intermediate frequency module in a corresponding digital intermediate frequency module group through one of the at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533), each of the at least one Tx port group (361, 362, 363, 441, 442, 443) comprises a plurality of Tx ports, a quantity of digital intermediate frequency modules comprised in each digital intermediate frequency module group is equal to a quantity of Tx ports comprised in a corresponding Tx port group (361, 362, 363, 441, 442, 443), each of the at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533) comprises at least two connection states, quantities of enabled digital intermediate frequency modules in a digital intermediate frequency module group connected to the each of the at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533) in different connection states are different, and all Tx ports in a Tx port group (361, 362, 363, 441, 442, 443) connected to the each one of the at least one switching switch (321, 322, 323, 431, 432, 433, 531, 532, 533) in the different connection states are in an enabled state.