A compact field hyperspectral imaging spectrometer based on a prism-grating-prism structure is presented. The system is designed for the wavelength range from visible light to near infrared. It has 344 spectral bands with the spatial resolution higher than 10 nm and the spectral resolution higher than 1 mrad. To study the unmixing of mixed pixels, the basic principle of the field hyperspectral imaging spectrometer is described, the main specifications of the system is analyzed, the design of the system is discussed in detail and related tests are conducted. The test results show that the system has both higher spatial resolution and higher spectral resolution. Because of its compactness and reliable operation, it is very suitable for field applications. Thus, the feasibility of the use of a compact field hyperspectral imaging spectrometer in the research on the unmixing of mixed pixels is verified.