The application effect of hyperspectral imaging relies heavily on the acquired signal-to-noise ratio (SNR) of images. The hyperspectral imaging requires a high frame rate and a low SNR for a high spatial resolution. The time-delay-integration (TDI) mode cannot be used to solve the problem of weak light energy, because the spectral imaging contains the two-dimensional spatial-spectral information. A swing mirror is usually used to reduce the application requirement. However, not only the volume and weight increase, but also the acquired image is discontinuous and the space reliability of the moving parts is reduced. Thus the ultra-high speed electron multiplication and the imaging spectroscopy are combined organically, and a high-resolution hyperspectral imaging chain model based on electron multiplication is built. This model can be used for a complete analysis of the SNR in an imaging chain, if all elements such as radiation source, object reflectance, atmospheric radiation transmission, optical system imaging, spectroscopic characteristics, detection spectral response and camera noise are comprehensively considered. The LOWTRAN 7 software is used to investigate the atmospheric radiation transmission. The illuminance at the image plane is calculated for different solar altitudes and object reflectance, and the SNR under different working conditions is calculated according to the noise model of an electron multiplying charge coupled device (EMCCD) detector. Through the analysis and experiment of SNR, a suitable choice of multiplication gain can make the SNR of weak spectral signals enhanced by 6 times.