According to the settlement monitoring device and method for a high-support formwork, a datum point is arranged at the lower end, stretches into and is fixed to a stand column of a bed rock layer, thestand column is supported by the bed rock layer with stable geological properties, the datum point arranged on the stand column cannot settle due to settlement of a soft soil layer in a correspondingarea, and therefore it is guaranteed that the datum point is kept still all the time; monitoring points are arranged on the high-support formwork and synchronously settle along with the high-supportformwork; an unmanned aerial vehicle, a camera and a laser range finder are matched, the vertical distance between the laser range finder and the reference point is H, the linear distance between thelaser range finder and a monitoring point is measured through the laser range finder, and the corresponding first linear distance L1, the corresponding second linear distance L2, the corresponding first angle [ alpha] and the corresponding second angle [beta] are obtained in sequence to be used for calculation and analysis, the vertical height change value D of the monitoring point is obtained, and therefore whether sedimentation happens to the high-support formwork or not and the sedimentation amount are accurately judged.