In order to reduce Electromagnetic Interference(EMI) and improve electric safety of the Airborne Electrooptical measuring system，reasonable grounding design is necessary. It’s issued in the paper that the principle and methods of grounding for safety and EMI. The grounding interference mechanism is expatiated also. Grounding interference and inhibition method of coupling circuit loop and common impedance are described also. The design characters of the grounding design are analyzed in system. It’s showed that perfect EMC performance of the system in practice. The main ways of Airborne Electrooptical measuring system’s grounding design may provide a reference of the similar engineering fields.