A calibration bracket , comprising a base , a stand assembly and a support assembly , the support assembly being configured to mount a calibration element; and the stand assembly being characterised by : a fixed vertical rod , one end of the fixed vertical rod being mounted to the base ; a movable vertical rod , mounted to another end of the fixed vertical rod , the movable vertical rod being movable relative to the fixed vertical rod only along a central axis, and the support assembly being mounted to the movable vertical rod ; a driving mechanism , comprising a first threaded rotating member , a second threaded rotating member and a threaded fixed member , the first threaded rotating member being mounted to the fixed vertical rod and being rotatable relative to the fixed vertical rod about the central axis, the second threaded rotating member having a first threaded structure and a second threaded structure spiraling about the central axis, a spiraling direction of the first threaded structure being the same as a spiraling direction of the second threaded structure, the second threaded rotating member being mounted to the first threaded rotating member through the first threaded structure and being mounted to the threaded fixed member through the second threaded structure, and the threaded fixed member being fixedly mounted to the movable vertical rod , wherein the fixed vertical rod has a mounting separator plate ; the first threaded rotating member comprises a journal portion , the journal portion being disposed at an end of the first screw portion ; and the journal portion is inserted in the mounting separator plate , and the cross-sectional dimension of the first screw portion is greater than a cross-sectional dimension of the journal portion , so that the first threaded rotating member is rotatable relative to the fixed vertical rod only about the central axis. a fixed vertical rod , one end of the fixed vertical rod being mounted to the base ; a movable vertical rod , mounted to another end of the fixed vertical rod , the movable vertical rod being movable relative to the fixed vertical rod only along a central axis, and the support assembly being mounted to the movable vertical rod ; a driving mechanism , comprising a first threaded rotating member , a second threaded rotating member and a threaded fixed member , the first threaded rotating member being mounted to the fixed vertical rod and being rotatable relative to the fixed vertical rod about the central axis, the second threaded rotating member having a first threaded structure and a second threaded structure spiraling about the central axis, a spiraling direction of the first threaded structure being the same as a spiraling direction of the second threaded structure, the second threaded rotating member being mounted to the first threaded rotating member through the first threaded structure and being mounted to the threaded fixed member through the second threaded structure, and the threaded fixed member being fixedly mounted to the movable vertical rod , wherein the fixed vertical rod has a mounting separator plate ; the first threaded rotating member comprises a journal portion , the journal portion being disposed at an end of the first screw portion ; and the journal portion is inserted in the mounting separator plate , and the cross-sectional dimension of the first screw portion is greater than a cross-sectional dimension of the journal portion , so that the first threaded rotating member is rotatable relative to the fixed vertical rod only about the central axis. <EOS>