The invention provides a scalable and visual large-
stroke caliper which is provided with a main scale, a fixed clamp leg, a flexible clamp leg, a handheld scalable rod, a connecting rod, a hand cranking controller,
horizontal angle and
vertical angle fine adjusting knob mechanisms, a displayer, a wide-angle camera, a spring, a first steel strand connected with the hand cranking controller, a second steel strand connected with the
horizontal angle fine adjusting knob mechanism, a third steel strand connected with the
vertical angle fine adjusting knob mechanism, a transverse pin shaft for realizing relative longitudinal rotation of the connecting rod and the handheld scalable rod, a longitudinal pin shaft for realizing relative transverse rotation of the connecting rod and the main scale, afirst
torsion spring which sleeves the transverse pin shaft and a second
torsion spring which sleeves the longitudinal pin shaft. When the size of the high altitude
structural component is measured,the caliper can extend to the surface of the measured component, the head of the caliper can moderately rotate to measure the component which cannot be seen, and the
technician only requires to operate on the ground so that the caliper is safe and reliable, accurate in measurement result, easy to operate and low in
measurement cost and solves the problem of danger caused by high altitude operation.