Abstract: Aiming at the deficiency of the detection method of the quiet area of the surrounding electromagnetic environment in radio astronomical observation, this paper proposes a radio interference monitoring method based on four-antenna linear array. The purpose is to monitor whether there are interference sources in the quiet area in real time and identify the incoming direction of the interference sources. The method is to use the portable four-antenna array to form a linear array, and use the MUSIC algorithm of the linear array to calculate the incoming wave direction of the interference source. Through the test under different distances and conditions indoors and outdoors, the results show that in a relatively open and quiet environment, the four-antenna array can effectively identify the incoming direction of the interference signal, and the reliability of the measurement angle error of no more than 5° is about 87%. After comprehensive analysis, it is concluded that the portable four-antenna linear array combined with MUSIC algorithm can better identify the direction of the incoming wave of the interference source in the radio astronomical observation in the open area, which can effectively help the radio telescope avoid the disturbed channel.