Abstract: Transient electromagnetic method (TEM) has a limited work scope in detecting the metal loss of buried pipeline due to the longer distance for the each detection point covered over pipeline, which is hard to meet the requirements of actual detection accuracy. Relative research is carried out on the focusing signal loading technology of magnetic field. A coil array applicable to detect buried metal pipeline is designed based on the magnetic focusing coil technology for cranio-cerebral stimulus, a genetic algorithm is used to optimize current magnitude and phase of the coil array, and magnetic field distribution of coil array in the calculation field and 2D isoheight maps are given. Numerical calculation indicates that the magnetic field produced by the coil array in the calculation field has a sound focusing function, providing a technique to the detection of corrosion for buried metal pipeline.