A calibration device for an on-board radar, the calibration device comprising a bracket assembly comprising: a base; a vertical rod disposed vertically, one end of the vertical rod being mounted to the base, wherein the vertical rod is provided with a rack, the rack being disposed vertically on the vertical rod; a sliding assembly movably mounted to the vertical rod and movable along the vertical rod, an accommodating hole being disposed on the sliding assembly; wherein the sliding assembly comprises a clamping member, a holder and a self-locking member, wherein the clamping member is sleeved on the vertical rod and is slidable along the vertical rod, and the clamping member is clamping the vertical rod to fix the sliding assembly to a required position; the self-locking member comprising a fine adjustment knob and an adjusting gear; wherein the fine adjustment knob is movably mounted to the clamping member, and the fine adjustment knob is rotatable relative to the clamping member; wherein the adjusting gear is sleeved on the fine adjustment knob, and the adjusting gear is meshed with the rack to fine adjust a height of the sliding assembly; a laser-corner reflecting apparatus mounted to the sliding assembly, the holder is fixedly mounted to the clamping member for supporting the laser-corner-reflecting apparatus, the laser-corner reflecting apparatus being movable relative to the vertical rod to adjust a height of the laser-corner reflecting apparatus; wherein the laser-corner reflecting apparatus comprises: a laser comprising a laser body, the laser body comprising a fixed shaft and a round emitting hole, the fixed shaft being perpendicular to the vertical rod, the fixed shaft being accommodated in the accommodating hole; and a corner reflector mounted to the laser; wherein the laser is configured to emit a laser to align a position of the corner reflector with that of the on-board radar, the corner reflector being configured to reflect a radar wave emitted by the on-board radar, so that the radar wave returns along an original path to calibrate an installation angle of the on-board radar. a bracket assembly comprising: a base; a vertical rod disposed vertically, one end of the vertical rod being mounted to the base, wherein the vertical rod is provided with a rack, the rack being disposed vertically on the vertical rod; a sliding assembly movably mounted to the vertical rod and movable along the vertical rod, an accommodating hole being disposed on the sliding assembly; a base; a vertical rod disposed vertically, one end of the vertical rod being mounted to the base, wherein the vertical rod is provided with a rack, the rack being disposed vertically on the vertical rod; a sliding assembly movably mounted to the vertical rod and movable along the vertical rod, an accommodating hole being disposed on the sliding assembly; wherein the sliding assembly comprises a clamping member, a holder and a self-locking member, wherein the clamping member is sleeved on the vertical rod and is slidable along the vertical rod, and the clamping member is clamping the vertical rod to fix the sliding assembly to a required position; the self-locking member comprising a fine adjustment knob and an adjusting gear; wherein the fine adjustment knob is movably mounted to the clamping member, and the fine adjustment knob is rotatable relative to the clamping member; wherein the adjusting gear is sleeved on the fine adjustment knob, and the adjusting gear is meshed with the rack to fine adjust a height of the sliding assembly; a laser-corner reflecting apparatus mounted to the sliding assembly, the holder is fixedly mounted to the clamping member for supporting the laser-corner-reflecting apparatus, the laser-corner reflecting apparatus being movable relative to the vertical rod to adjust a height of the laser-corner reflecting apparatus; wherein the laser-corner reflecting apparatus comprises: a laser comprising a laser body, the laser body comprising a fixed shaft and a round emitting hole, the fixed shaft being perpendicular to the vertical rod, the fixed shaft being accommodated in the accommodating hole; and a corner reflector mounted to the laser; a laser comprising a laser body, the laser body comprising a fixed shaft and a round emitting hole, the fixed shaft being perpendicular to the vertical rod, the fixed shaft being accommodated in the accommodating hole; and a corner reflector mounted to the laser; wherein the laser is configured to emit a laser to align a position of the corner reflector with that of the on-board radar, the corner reflector being configured to reflect a radar wave emitted by the on-board radar, so that the radar wave returns along an original path to calibrate an installation angle of the on-board radar.