Abstract: To address the blackout problem faced by hypersonic vehicles during atmospheric reentry, a blunt-body model is established based on flight test data from radio attenuation measurement project of national aeronautics and space administration, and the frequency distribution of the plasma flow field is numerically simulated around hypersonic vehicle in the blackout zone. The frequencies at the communication window are fitted with a function, and based on this function, the propagation characteristics of electromagnetic waves in non-uniform plasma are simulated. The research results indicate that the blackout problem is most severe for hypersonic vehicle with a reentry altitude of 47 km and a flight Mach number of 20. Applying a 1.2 T magnetic field at the vehicle′s magnetic window can reduce the electron density by 0.01 %, thereby decreasing collisions between charged particles, broadening the electromagnetic wave communication band, and alleviating the vehicle′s blackout problem. When the flight altitude of the vehicle is 71 km, electromagnetic waves in the L-band and VHF band are prone to communication interruptions, but an external magnetic field of 3.3 T can enable normal communications in these bands. The findings of this study provide a solution and theoretical basis for using external magnetic fields to mitigate blackout issues in hypersonic vehicles.