In order to improve the electromagnetic protection ability of communication radio station and reveal the blocking interference effect of single frequency electromagnetic radiation on the communication radio station，the nonlinear analysis of the receiving link of communication radio station is conducted，and then taking a certain type of communication station as the test object，the electromagnetic radiation experiments are carried out under the fixed frequency communication state.The results show that single frequency electromagnetic radiation is easy to cause the increase in bit error rate of communication radio and even lead to communication interruption，and the bit error rate is positively correlated with the intensity of interference signal.When the bit error rate increases to about 22%-23%，the increase in the radiation field strength will lead to communication interruption.The operating frequency has a great impact on the anti-blocking interference ability of radio station.The sensitive frequency band of the tested communication radio station is about (

f

0

-60)-(

f

0

+60)kHz.When the radiation frequency offset is within the range of ±1MHz，the critical interference field strength under different operating frequencies increases with the expansion of radiation frequency offset at both ends，and there is a clear size relation

ship of the critical interference field strength.Beyond this range，the critical interference field strength will be ups and downs with different levels，with different levels.In a certain range，enhancing the useful signal will improve the critical interference field strength，and the improvement times of the two are similar.The strength of the useful signal can be enhanced to significantly improve the anti-blocking interference ability of communication station.