The rapid development of smart grid shows great demand for high-performance sensors. Thus

we designed a current sensor device with high voltage

wide frequency band

and large current based on giant magneto resistance effect

including the amplifier module

filtration module

degaussing module

and power module. The electromagnetic shielding of the device was also designed in terms of the operation environment with strong electromagnetic interferences. The calculation results indicate that the device’s shielding effectiveness to the external magnetic field can reach 41.6 d B. It is proved by electromagnetic compatibility test that the developed device can effectively suppress the external electromagnetic interferences. Meanwhile

the accuracy of the current sensor device in measuring the lightning current can be more than 93.9% in the experiment. Therefore

aiming at measuring large current with wide bandwidth of DC-10 MHz in the smart grid

the proposed current sensor device has great advantages over current sensors based on other techniques and prospects in measuring large current with wide bandwidth in smart grid.