A compact static infrared snapshot imaging spectrometer (ISIS) is designed in order to satisfy the application requirements of real-time spectral imaging for the moving targets. It consists of a CDP (crossed dispersion prism), an imaging lens, and a detector. Here we describe the spectral imaging principle, and design a short wave infrared imaging spectrometer with 4.8° field of view, the measured spectrum is from 0.9µm to 2.5µm and is sampled by 40 spectral channels. This instrument has a large potential for detecting, locating and identifying unknown energetic events in real-time.