The grating is the core component of the grating spectrometer. The dispersion ability of the grating determines the spectral resolution of the spectrometer directly. The spectrometer based on the immersed grating uses the immersed grating as the dispersion component. The equation of the spectral resolution of the immersed grating is derived. With the same requirement of the spectral resolution, comparing the immersed grating with the ordinary reflection grating, using the immersed grating can realize high spectral resolution while greatly decreasing the volume and the weight of the spectrometer. The material of the immersed grating, the applications of the immersed grating in spaceborne and ground-based high spectral resolution spectrometers, and the manufacturing methods of the immersed grating are introduced. A 70 mm silicon immersed grating was designed and developed. The measured grating efficiency is >57%, the measured grating polarization is <3.2%, and the test results of all specifications meet the technical requirements.