Imaging spectrometers are capable of acquiring information in both the spatial and spectral dimensions of a target, and have been widely used in agriculture, industrial production, military and other fields. To comply with the development trend of unmanned aerial vehicle (UAV) lightweight development trend on the imaging spectrometer load miniaturization, lightweight requirements, and at the same time to ensure the high imaging quality, high spectral resolution of the performance needs, a new type of lightweight and small self-aligned PG imaging spectrometer optical system design is proposed. The thesis combines a Dyson-type imaging spectrometer and prism-grating-prism (PGP) features through an in-depth study of existing imaging spectrometer types. The introduction of the image-space telecentric lens at the same time to assume the function ofcollimating lens and imaging lens, greatly reducing the size and quality of the optical system, effectively reducing the cost of processing, assembly and adjustment; the use of prisms and plane reflective grating combination constitutes the PG dispersion module, instead of concave grating, and at the same time retains the ability to correct the spectral bending of the PGP. The designed imaging spectrometer features a slit length of 10 mm, a working wavelength range of 450 to 900 nm, a relative aperture of 1∶3, and a full spectral resolution of better than 0.8 nm when the slit width is 10 μm. The envelope volume of the optical system is only 123 mm×44 mm×44 mm, and the MTF of the full field of view exceeds 0.5 at 100 lp·mm^-1 , approaching the diffraction limit. The RMS of each wavelength point array is smaller than that of the Airy spot indicating good imaging quality of the system. Sodium dual line separation can be effectively achieved under laboratory conditions.