An antenna downtilt adjustment apparatus, comprising a first transmission assembly, a flexible transmission assembly, and a second transmission assembly that are disposed on a mounting plate, wherein - the flexible transmission assembly comprises a transmission element and a guiding element; the transmission element is in an integrated long strip shape and bendable, one end of the transmission element mates with the first transmission assembly, and the other end of the transmission element mates with the second transmission assembly; the guiding element is secured to the mounting plate, and the guiding element is configured to constrain an extension path of the transmission element on the mounting plate; the first transmission assembly is configured to be driven by an antenna information management module, and to transmit a force to the second transmission assembly by using the transmission element; and the second transmission assembly is configured to drive a phase shifter; - the guiding element comprises a securing part, a connecting part, and a mating part, the securing part is configured to be securely connected to the mounting plate, the connecting part is connected between the securing part and the mating part, and the mating part is configured to mate with the transmission element, to guide and support installation of the transmission element on the mounting plate; - a through hole is provided in the connecting part, and the through hole is provided between the mating part and the securing part; - the securing part 341 is either of a snap-fit structure or of a screw assembly structure including a pair of screw holes; - wherein * either the second transmission assembly is a straight pull rod, one end of the straight pull rod is secured to the transmission element, and the other end is secured to the phase shifter; and the first transmission assembly drives the transmission element to move, to push or pull the straight pull rod or * the first transmission assembly drives the transmission element to rotate, the second transmission assembly comprises a worm and worm wheel assembly, and a rotational motion of the transmission element drives a rotational motion of the second transmission assembly, and drives the phase shifter to rotate. - the flexible transmission assembly comprises a transmission element and a guiding element; the transmission element is in an integrated long strip shape and bendable, one end of the transmission element mates with the first transmission assembly, and the other end of the transmission element mates with the second transmission assembly; the guiding element is secured to the mounting plate, and the guiding element is configured to constrain an extension path of the transmission element on the mounting plate; the first transmission assembly is configured to be driven by an antenna information management module, and to transmit a force to the second transmission assembly by using the transmission element; and the second transmission assembly is configured to drive a phase shifter; - the guiding element comprises a securing part, a connecting part, and a mating part, the securing part is configured to be securely connected to the mounting plate, the connecting part is connected between the securing part and the mating part, and the mating part is configured to mate with the transmission element, to guide and support installation of the transmission element on the mounting plate; - a through hole is provided in the connecting part, and the through hole is provided between the mating part and the securing part; - the securing part 341 is either of a snap-fit structure or of a screw assembly structure including a pair of screw holes; - wherein * either the second transmission assembly is a straight pull rod, one end of the straight pull rod is secured to the transmission element, and the other end is secured to the phase shifter; and the first transmission assembly drives the transmission element to move, to push or pull the straight pull rod or * the first transmission assembly drives the transmission element to rotate, the second transmission assembly comprises a worm and worm wheel assembly, and a rotational motion of the transmission element drives a rotational motion of the second transmission assembly, and drives the phase shifter to rotate. * either the second transmission assembly is a straight pull rod, one end of the straight pull rod is secured to the transmission element, and the other end is secured to the phase shifter; and the first transmission assembly drives the transmission element to move, to push or pull the straight pull rod or * the first transmission assembly drives the transmission element to rotate, the second transmission assembly comprises a worm and worm wheel assembly, and a rotational motion of the transmission element drives a rotational motion of the second transmission assembly, and drives the phase shifter to rotate.