Abstract: Based on the dynamic monitoring of the water flow in the underground open channel of Yaoqiao Coal Mine, a robot is designed that can automatically measure the sediment thickness of the open channel to solve the problem of inaccurate measurement of open channel flow caused by excessive sediment deposition in the open channel. The robot is coaxially linked by a motor, an encoder and a lead screw, and the motor rotates to drive the screw and the encoder to rotate. The extension length of the mechanical arm is calculated by the number of motor rotation recorded by the encoder and the lead screw lead, and then the measured amount of sediment deposition thickness is calculated. Through repeated measurements, it is confirmed that the measuring robot has the repeat error of less than 1 mm in the range of 500 mm, and the data transmission is stable and reliable.