The invention discloses a multi-rotor unmanned aerial vehicle monitoring method and system based on flight airspace division. The method comprises the following steps: dividing to-be-monitored airspace into two large airspaces: low altitude airspace and high altitude airspace, and then dividing the two large airspaces into a plurality of sub-airspaces; and identifying an invasive unmanned aerial vehicle in the monitor by using an image identification and object detection technology. Through the method and system disclosed by the invention, the high altitude sub-airspace is continuously extended outwards along the increasing of the altitude, thereby giving longer reaction time for the monitoring system; a telephoto lens can shoot more high-definition pictures to improve an accuracy rate ofthe image identification, thereby improving the accuracy rate of the whole monitoring system; and the unmanned aerial vehicle can be identified faster in an unmanned aerial vehicle invades a designated region. The invention provides a relatively perfect airspace division method and monitoring system, and the problem that the invading unmanned aerial vehicle is hard to be detected is solved.