With the acceleration of urbanization in China, in order to ensure the effective operation of the city, it is necessary to effectively manage the urban underground pipeline, which requires the support of corresponding underground pipeline detection technology. In view of this situation, the underground pipeline detector is used for underground pipeline detection and positioning, buried depth and pipeline insulation fault point search. At present, it is the most effective detector and tester for detecting various underground pipelines such as gas, electric power, telecommunications, tap water, drainage and cable TV. It is composed of a transmitter, a receiver and accessories for accurate positioning of underground pipeline route, buried depth measurement and long-distance tracking, as well as measurement and search of pipeline insulation fault points. Underground pipeline detector is also known as: pipeline detector, underground pipeline detector, underground pipeline fault identifier, underground pipeline fault tester and underground pipeline tester. Classification, content and technical terms of underground pipelines 1. Classification and content of underground pipelines (1) water supply pipeline: it can be divided into domestic water, production water and fire water according to the purpose of water supply; (2) Drainage pipeline: according to the nature of discharged water, it can be divided into sewage, rainwater, rainwater sewage confluence, industrial wastewater and other pipelines. (3) Gas pipeline: it can be divided into gas pipeline, liquefied gas pipeline and natural gas pipeline according to the nature of the gas transmitted; According to the pressure P of gas pipeline, it is divided into low-pressure, medium pressure and high-pressure pipeline, and other categories are based on low-pressure P ≤ 5kPa; Medium pressure P & gt; 5kPa,≤ 0.4MPa; High pressure P & gt; 0.4MPa, ≤ 1.6Mpa. Structure of power pipeline (1) equipment and structures of power pipeline: including power plant, substation, distribution station, distribution box, inspection well, etc. (2) Buried type of power pipeline 1) direct burial: the cable is buried in the trench, covered with soft soil, and the protective plate is set on it. 2) Cable trench or trough box: closed pipe trench without passage, and the cover plate can be opened; 3) Pipe burying: pipe block and pipe burying; 4) Cable tunnel. (3) The branch form of power cable adopts T-shape or Y-shape. (4) Cable material: aluminum core or copper core. (5) Power cable function: divided into power supply (transmission and distribution), street lamp, tram, etc. (6) Voltage of power cable: it is divided into low voltage, high voltage and ultra-high voltage. The common voltages of power cable are: 0.22kv, 0.38kv, 1kV, 6kV, 10kV, 35kV, 110KV, 220kV, etc. Underground pipeline detection method is one of the commonly used geophysical detection methods. Generally, there are two methods: the first is to use DC detection method for geophysical detection. Specifically, in the process of detection, two power supply electrodes are mainly used for corresponding DC power supply, and a power supply cycle is formed underground, Through the circulating power supply to ensure the measurement of underground current density, we can effectively judge the specific location of buried metal pipelines. Generally, the detection using this method is mainly based on the corresponding metal pipeline. This method is based on the difference of current density. Generally, the most commonly used method of this technology is the high-density resistivity method for corresponding measurement. For example, during the measurement of underground pipelines in a city, the direct current detection method is used for geophysical detection, and the location of metal pipelines in concrete materials is effectively found; The second method is to use the alternating current detection method for geophysical detection. Specifically, in the process of detection, the corresponding conductivity and corresponding magnetic transformation generated by the alternating current in the process of magnetic field transformation are mainly used. In the process of detection, the corresponding underground pipelines are detected through the magnetic field formed by the alternating current, So as to effectively ensure the accuracy of underground pipeline detection. Through the use of alternating current detection method for geophysical exploration, we can effectively find the differences between underground media, and find out the specific problems and sources of these differences through the analysis of these differences. Specifically, these methods have the characteristics of uniform measurement and long working time. They are one of the effective means for underground pipeline detection.