The Hyperspectral Environmental Suite (HES) on the next generation of Geostationary Operational Environmental Satellite (GOES-R) will provide hyperspectral Infrared (IR) measurements with high spatial and high temporal resolutions for soundings. To study the impacts of these measurements on the temperature and moisture profile retrievals, different spectral coverage, spectral resolution, and signal to noise ratio (SNR) have been tested for a hyperspectral IR sounder on the geostationary satellite. Based on a fast forward radiative transfer model, the retrieval simulation has showed that the hyperspectral IR sounder with properly chosen spectral coverage, spectral resolution and SNR can achieve the science performance requirement for 1K for temperature retrieval accuracy and 10% for relative humidity retrieval in the lower atmosphere. The effect of above spectral parameters on the vertical resolution of retrieval is also investigated by the data density method. In addition, the blurring error, caused by the energy diffraction outside the single field of view, and its impact on the sounding retrieval is demonstrated through a point spread function tool. These studies will help define the geo-satellite IR sounding instrument to meet the users' requirement.