The necessity of using high-resolution near infrared spectra in space-based atmospheric CO2 detection is discussed. According to simulation results, some key parameters such as detection band, spectral resolution and singnal to noise ratio (SNR) for space-based CO2 detection are analysed. Based on these simulated parameters, a spatial heterodyne spectroscopy (SHS) prototype instrument is introduced. Then this prototype instrument′s spectral resolution and abilities in CO2 detection are verified by laboratory and out-door experiments. Using LBLRTM software and near-real-time atmospheric parameters acquired from National Centers for Environmental Prediction (NCEP), the ground-based observation data of the instrument is simulated. The comparison between simulation results and SHS prototype instrument′s measurements shows a good fit. It is proved that the SHS prototype instrument is very sensitive to atmospheric CO2 absorption, and the instrument′s measurements could be used for space-based atmospheric CO2 detection.