To suppress the magnetic interference on grounding system caused by air-core reactors, two kinds of schemes to reduce the induced current of grounding system are proposed, one is to adopt independent secondary grounding body, the other is to adopt radial grounding grid structure. In this paper, the current of secondary cable shielding layer and grid grounding network is measured in a 500 kV substation. According to the reverse-voltage theoretical model and on site experiment results, the effect of adding independent secondary grounding body for shileding layers of different lines is analyzed. Futhermore, a 3D electromagnetic model is built to simulate and compare the anti-interference effect for radial grounding grids. The emulational data and experimental reasults show that by using secondary grounding body, more than half of the induced current can be reduced, and the radial grounding grids under reactor can suppress the magnetic interference effectively.