The use of transient electromagnetic method and harmonious electromagnetic method instrument to observe the underground space data and perform fusion processing can improve the detection imaging ability, but most of the existing transient electromagnetic method and harmonious electromagnetic method instruments are independent sets and must be equipped with multiple sets to separate collection. A small size, large bandwidth and high sensitivity electromagnetism transceiver coil that can meet the use of both transient / harmonic modes is designed to lay the foundation for the development of portable, shallow and high resolution transient / harmonic integrated electromagnetic detection system. First, the equivalent circuit model of the air-core coil sensor is established, and the sensitivity and noise characteristics of the coil-core sensor are analyzed, the test results of the air-core sensor show that at 1 125 Hz, the sensitivity is 23. 12 mV/ nT, the equivalent magnetic noise is 9. 27 pT / √Hz and the bandwidth is 1 Hz~ 100 kHz. Then, the formula and finite element analysis software are used to calculate the transceiver coupling relation when the sensor coils are placed eccentrically, and the optimal eccentric location of the combination of transceiver coil is determined, the calculation and simulation results differ from actual location by 0. 21% and 0. 17% respectively, which effectively eliminated the launch magnetic field (primary field). Finally, the time-domain and frequency-domain electromagnetic method systems are constructed, and the test results show that the designed transient / harmonic integrated transceiver coil can meet the needs of time-domain and frequency-domain electromagnetic detection modes.