The utility model relates to a SF6 gas reactor magnetic shielding structure which is arranged in an annular magnetic shielding layer in a non-magnetic conductive casing of a reactor. The magnetic shielding layer is arranged on the housing wall of the reactor, and the upper and lower ends of the magnetic shielding layer are fan-shaped magnetic conductive materials superposed on each other in a staggered manner. In the utility model, excellent magnetic conductive materials are employed to build an annular shielding structure in a non-magnetic-conductive non-metallic armoured casing of a reactor. Magnetic leakage generated by windings is introduced back into a magnet circuit, which reduces diffraction of magnetic leakage at the armoured casing and minimizes heat generation of the armoured casing. The SF6 gas reactor magnetic shielding structure is also applicable to oil-immersed reactors.