A measurement system is provided to measure a hole of a target, including a light source generation unit, a capturing unit and a processing unit. The light source generation unit generates a light source and focuses the light source on a plurality of different height planes. The capturing unit captures a plurality of images scattered from the plurality of different height planes. The processing unit obtains boundaries of the hole on the plurality of different height planes according to the plurality of images, samples image intensities of different azimuth angles on the boundaries of the hole on each of the plurality of different height planes to generate a plurality of sampling values, and develops a sidewall image of the hole according to the plurality of sampling values, the plurality of different height planes and the different azimuth angles.