Abstract: The high-density resistivity method is a high-efficiency, high-precision exploration technique. In recent year it has been more and more widely applied in geotechnical engineering investigation. This paper briefly summarizes the status and areas of application of high-density resistivity exploration and introduces the basic principle of high-density resistivity exploration and procedures of the MN-B pole-dipole resistivity measurement instrument. The data gathering, data processing, geological interpretation and existing problems concerning the MN-B pole-dipole measurement instrument are dealt with in details according to the material field survey on the construction road for the west-to-east gas pipeline project. The survey results show that this high-density resistivity method has shown many advantages in the material field survey on the construction road for the west-to-east gas pipeline project and yielded good results. It plays an irreplaceable role in rapid material field survey, determination of the thickness of the useful layer of the material field and accurate calculation of the reserves of material fields.