Civil aviation radio frequency dedicated to several types of sources of interference are: the first category for the illegal setup of radio stations, the second category for the unreasonable setup of legal radio stations generated by intermodulation interference, the third category for individual industrial medical equipment. Among them, the illegal setting of the use of radio stations (stations) is the main source of interference, at present they can be divided into two categories, one is the illegal use of high-power cordless phones; the other is the unauthorized expansion of the power of the radio and television transmitters; and before some of the illegal setting of the high-power paging transmitters, with the shrinking of paging business caused by the intermodulation of interference events and gradually disappeared; the other (not associated with the broadcasting and television transmitters) has been found to be the unreasonable setting of the intermodulation generated by the radio and television transmitters, and the third category is individual industrial medical equipment. Other (not associated with broadcasting and TV transmitters) have been found to have intermodulation interference generated by unreasonable settings of legal stations and individual industrial medical equipment, after a series of scientific management and adjustment over the years, their interference has been eliminated. The basic features of the current distribution of these two types of major sources of interference are that the distribution of high-power cordless telephones has gradually shifted from cities to rural areas or towns, and that civil aviation airports and flight paths are located in rural areas far away from the cities, thus making them an increasing threat to the safety of civil aviation flights. The unauthorized expansion of the power of radio and television transmitters are mainly distributed in cities and counties, due to its transmit power is too large, easy to form intermodulation interference with other transmitting equipment, affecting the normal use of other radio receiving equipment, has always been a threat to the civil aviation flight safety of the source of interference.