A capacitive digital caliper comprises a main beam and a second beam, a rack and a gear are mounted on the main beam and the second beam, respectively. This gear system changes the line position x on the main beam into angular position (Q+2n pi ), and the angular position is measured by a capacitive measuring assembly. The capacitive measuring assembly for angular position is seally isolated from the rack and fear by a seal cavity and a seal member. Therefore, the caliper can be used in poor environment under the influence of particulate and fluid contaminants. The present invention is particularly suitable for being used in the field of mechanical work.
