The utility model provides a novel bridge pier column diameter is measured device which characterized in that: including 2 grade at least extension rule body (1), connect through guide rail (3) between adjacent extension rule body (1), the position of rest of scale is equipped with level bubble (6), and telescopic straight bar (4) is connected at blade (1) both ends. The utility model discloses a blade is the shaft -like structure of telescopic to set up gram telescopic straight bar at blade both ends, can realize the measurement to not unidimensional bridge pier column diameter through cooperation between them, the cooperation through the level bubble simultaneously, the measuring error that reduces.