The invention relates to a device which utilizes a rotating low frequency magnetic field to remotely control the movement of a crawler in a pipeline outside the pipeline, which consists of two parts of an electric instruction source and an electronic transducer, wherein, the electric instruction source generates a low frequency radiation magnetic field outside the pipeline; the electronic transducer arranged on the crawler receives the low frequency magnetic field sent by the instruction source in the pipeline, carries out magnetic field analysis, and sends out a positioning instruction, thus causing the crawler to stop at a specified position. The device of the invention has the advantages that: (1) no radioactive elements exist, which prevents operators from being threatened by radiation and avoids the pollution of the radiation to environment; (2) no danger exists in transportation, storage, use and post-processing, no special protective measures are needed to be adopted, thus being simple, convenient and easy to operate; (3) a magnetic medium instruction locator can completely substitute the traditional Gamma-ray source, with high positioning accuracy.