In order to meet the requirement of instantaneous imaging technology for transient optical system, a method of instantaneous luminescence based on perovskite nanometer crystal random maser is proposed in this paper. Based on the preparation and characterization of CsPbBr₃ nanometer crystal films, the preparation methods and means of similar active films are analyzed. Combined with the application needs, this paper designed the electron beam pumping structure with microchannel plate as the core, and verified the maser effect of CsPbBr₃ nanometer crystal film under electron beam pumping through experiments, and analyzed its maser principle and physical phenomenon. Finally, the instantaneous advantage of CsPbBr₃ nanometer crystal thin film is verified by instantaneous optical pumping. In the instantaneous detection system of the new developed film, not only has good transient characteristics and time resolution, but also can use the electron beam pumping to induce laser to form the second stage of light amplification, thus improving the overall detection ability of the device.