Previous studies mainly focus on electromagnetic environment simulation of electromagnetic launching device, but rarely take account of the magnetic protection. According to the minatory characteristics of electromagnetic radiation and Electro-Magnetic Interference(EMI) which the electromagnetic launching device’s enclosure is exposed to, and based on the Finite Integration Technique(FIT), the simulation research of magnetic shielding character of the device enclosures is conducted and the magnetic field shielding characteristics of the device are studied. Taking a device for example, the maximum magnetic flux density is 10 T, the main frequency is below 5 kHz, and the magnetic frequency is 40 dB, which meets the design requirements of the system magnetic protection.