The acquisition of hyperspectral image dataset of the earth from space with high accuracy of spectrum and radiation is the objective that a number of space missions dedicate to, which is critical to studying and quantifying aquatic environments, wildfires, coastal ecosystem, and atmospheric composition. In this paper, a hyperspectral imager in geostationary orbit ranging from ultraviolet to longwave infrared is proposed. Geostationary perspective has the capability to provide high temporal, spatial, and spectral resolution measurements. The optical system employed in the proposal is composed of an ultra-large aperture afocal system, three telescope subsystems, and five spectral channels with area array image detectors. The key parameters of the system are identified through analyzing and optimizing of system architecture and specification.