The invention discloses a prismatic decomposition multiplexing multi-spectral imaging device which comprises a telescopic objective set, an entrance slit, a collimating mirror, a beam splitter prism, a first way of imaging module, a second way of imaging module, a third way of imaging module, a control circuit and a computer controlling and image collecting and processing system. Three kinds of different spectrum images can be obtained at the same time through one beam splitter prism and three imaging light paths, multiplexing multi-spectral imaging is achieved, and feature images can be directly merged without subsequent image processing due to the high spectral resolution of the formed images. According to the prismatic decomposition multiplexing multi-spectral imaging device, only three kinds of spectrum images with different characteristics of the same scene target are received each time, the real-time performance of an imaging system is improved, and engineering application is facilitated. The prismatic decomposition multiplexing multi-spectral imaging device is simple in structure, characteristic multi-spectral combinations are conducted on a specific target conveniently so that fast detection and recognition can be achieved, various characteristic spectral combinations can be achieved, and therefore detection and recognition of disguise targets of various backgrounds of different season vegetations, deserts and water bodies can be achieved.