Graduated scale convenient for marking root canal length

The utility model discloses a graduated scale convenient for marking the length of a root canal. The ruler comprises a graduated scale and a ring, the ring is arranged at the center of the back surface of the graduated scale; the finger ring is connected with the graduated scale in an integral casting manner; a strip-shaped groove is formed in the middle of the front face of the graduated scale inthe long edge direction. The upper end of the strip-shaped groove is in a slope shape and ends at the upper end of the strip-shaped groove. An oval groove is formed in the lower end of the strip-shaped groove; scale marks are arranged on the right side, corresponding to the strip-shaped groove, of the front surface of the graduated scale; a T-shaped sliding groove is formed in the left side of the graduated scale in the long edge direction. And a sliding block matched with the T-shaped sliding groove is arranged in the T-shaped sliding groove in a sliding manner, the tail end of the sliding block is vertically connec