The oblique tube is usually installed in a vertical borehole that passes through the unstable soil layer to the lower stable stratum. The deformation of the oblique tube is observed by using a digital vertical active inclinometer probe, a control cable, a pulley device and a reading meter. The first observation can establish an initial section for measuring the displacement of the oblique tube. Subsequent observations will show changes in the displacement of the section during motion at the local surface. At the time of observation, the probe moves from the bottom of the oblique tube to the top, pauses at half a metre spacing and carries out the measurement tilt work. The tilt of the probe is measured by two force-balanced servo accelerometers. An accelerometer measures the longitudinal position of the groove of the oblique tube, that is, the inclination of the plane on which the measuring wheel is located on the inclinometer probe. Another accelerometer measures the tilt perpendicular to the plane of the measuring wheel. The tilt can be converted to a lateral displacement. Comparing the current and initial observation data, the variation of lateral offset can be determined, which shows the motion displacement of the formation. A high-resolution displacement sectional diagram can be obtained by drawing the variation of the offset.This sectional diagram helps determine the size, depth, direction and rate of ground motion displacement.