The invention relates to a pair of two-section calipers for measuring the inner diameter of an insulator edge slot. The pair of two-section calipers is characterized in that the pair of two-section calipers includes a scale (1), a hinged column (5) is fixedly installed in the middle of the scale (1), the top end of a left large arm (2) and the top end of a right large arm are hinged to the hingedcolumn (5), the bottom end of the left large arm (2) and the top end of a left small arm are hinged to each other, the bottom end of the right large arm and the top end of a right small arm (3) are hinged to each other, and the left small arm and the right small arm (3) are each provided with a through hole (4) in the bottom end; and the pair of two-section calipers further includes a first springwire and a second spring wire (6), wherein one end of the first spring wire is tied to the through hole (4) in the bottom end of the left small arm, the other end of the first spring wire is tied tothe scale (1), one end of the second spring wire (6) is tied to the through hole (4) in the bottom end of the right small arm (3), and the other end of the second spring wire (6) is tied to the scale(1). The measurement result obtained using the pair of two-section calipers is intuitive and reliable.