To reduce the electromagnetic radiation emission intensity of airborne digital equipment， the spectrum of the digital signal is analyzed， revealing that the fundamental wave and its high-frequency harmonics are the sources of electromagnetic radiation emissions. Next， the rationale of shielding layer to suppress electromagnetic radiation is analyzed. The results indicate that the high-conductivity non-magnetic shielding layer has a good shielding effect on the electric field and high-frequency magnetic field. The influence of the gap on the shielding effectiveness of the shield is analyzed again， and a new method of double-layer fill shielding is proposed and validated. Then， the absorption loss of the electromagnetic wave is analyzed， and a new method for improving the shielding effectiveness of twisted-pair shielded cable/coaxial cable double-layer shielding is proposed and validated. Finally， an actual engineering project is considered as an example. The project equipment satisfies the GJB151B-2013 RE102 requirements and still interferes with the Beidou equipment Star（BDS） Searching and positioning. The electromagnetic compatibility is improved using the proposed method. After the improvement， the emission intensity of electromagnetic radiation is significantly reduced， by 12 dBμV/m on average. The ground and flight experiments verify that the integral power of the BDB1 and BDB3 frequency points is increased by 0.59 and 1.84 dBm， respectively， under normal operating conditions， and the number of BDS searching satellites is increased from ≤3 to ≥9， the BDS can operate normally.