With the development of satellite communication technology, the traditional spectrum monitoring mode is difficult to meet the monitoring needs. In order to meet the urgent needs of modern satellite signal receivers for larger bandwidth, higher resolution and stronger real-time processing, an automatic broadband spectrum monitoring system was developed. The system realizes the large-bandwidth and high-resolution display of the satellite signal spectrum through RF direct sampling technology and channelization processing. Experimental results show that the system can monitor the L-band signal in real time and generate the panoramic spectrum of the L-band signal with a spectral resolution of less than 1 kHz. Through the in-depth analysis of spectrum data, the system can automatically identify and store signal parameters, and its portability and flexible design make the system flexible to deploy a variety of application scenarios, which perfectly fits the development direction of modern satellite signal receiver technology.