The invention discloses an unmanned plane monitoring system based on a software radio. The system comprises at least one horn antenna used for scanning and monitoring an air unmanned plane, a front radio frequency terminal used for receiving and processing a wireless signal scanned by the horn antenna, a down conversion module which is connected with a first output port of the front radio frequency terminal and is used for receiving a radio frequency signal sent by the first output port of the front radio frequency terminal and carrying out down conversion for the radio frequency signal to acquire an L-band radio frequency signal, an FPGA core processing module used for carrying out acquisition, calculation and analysis of the L-band radio frequency signal to acquire carrier wave center frequency of the unmanned plane and calculating and determining the position orientation of the unmanned plane according to the carrier wave center frequency, and a PC carrying out bidirectional communication with the FPGA core processing module. The unmanned plane monitoring system solves detection sensitivity, volume and information exposure problems existing in radar equipment in the prior art.