The utility model discloses a tank wall verticality measuring device which comprises a horizontal plate and a receiving plate, a transverse gradienter and a longitudinal gradienter are arranged above the horizontal plate, two sets of clamping blocks are arranged in the middle of the lower portion of the horizontal plate, first locking bolts are arranged on the clamping blocks, a round hole is formed in the front end of the horizontal plate, and a
laser pen is vertically fixed in the round hole. A second locking bolt is arranged on the front side face of the horizontal plate to fix the
laser pen, the receiving plate is placed on the ground, a cross target center is arranged on the surface of the receiving plate, and the receiving plate is arranged below the
laser pen. The device can be directly clamped on the side edge of the tank body, is simple to
mount and operate, has good stability, can be repeatedly used, can be monitored at any time, is beneficial to timely deviation correction, performs measurement by utilizing the characteristics that the laser pen is stable in long-range emission effect and easy to observe, has high
measurement precision, and improves the construction quality and the measurement efficiency.