The embodiment of the invention provides a measuring weir measuring device. The measuring weir measuring device comprises a stepping motor, a ball screw which is driven by the stepping motor to move up and down, an electrode which is arranged at the second end of the ball screw, a probe which is driven by the ball screw to move up and down, a current sensor which sends out a triggering signal whenthe second end of the probe just makes contact with the liquid surface of liquid in a measuring weir and detects currents, and a processor which forwards the triggering signal to trigger the steppingmotor to stop working, wherein the second end of the electrode is kept in the liquid in the measuring weir, and when the second end of the probe makes contact with the liquid in the measuring weir, the electrode and the probe form a conductive circuit through the liquid in the measuring weir, the distance between the second end of the probe and the water head high point of the measuring weir is calculated according to the step number of the stepping motor, the height of the liquid surface of the liquid in the measuring weir is calculated according to the known second distance and the known first distance, and the seepage flow is calculated according to the height of the liquid surface of the liquid in the measuring weir.