Abstract: Positioning principle of pipeline blockage clearing robot was introduced, the distribution regularities of extremely low frequency electromagnetic signals outside the pipe were analyzed according to magnetic dipole model, one-dimensional positioning method of pipeline blockage clearing robot was established, and electromagnetic positioning system of pipeline blockage clearing robot was designed. Experimental results show that the system can achieve effective positioning of robot, when receiving antennas moves at speed of 5 m/s and 10 m/s, mobile positioning error ranges are -20.7-19.8 cm and -24.3-27.1 cm, which can fully meet project accuracy requirements.