Airborne magnetometry has a long and fruitful history in many applications. The acquired data are usually contaminated by noises originated from a variety of sources, which migrates the effectiveness of the system on detecting magnetic targets. In this paper, a large loop with DC current is designed, serving as a manmade magnetic target. Then, an experiment for helicopterborne magnetometry is performed to measure the induced magnetic field at different elevations. The acquired data after denoising can be used to calibrate the airborne magnetometry system which will be further applied to aeromagnetic measurement or magnetic targets detection. The data processed result shows a good performance for the system because it is capable of detecting a magnetic target of a few nT at a long distance.