In view of disruption caused by spacecraft reentering into the atmosphere and experiencing the black area, the cause of the black-out was described. Through analysis of the propagation characteristic of the electromagnetic wave in plasma that affects different frequencies of radio waves to transmit, the higher frequency band applied to space TT&C to resolve the problem of the spacecraft communication discontinuity in the blackout area was discussed. It's indicated that the plasma model of the blackout area, correction of the electromagnetic wave propagation in plasma, how to overcome the effect of rain on transmission attenuation and so on should be analyzed and researched further.