Due to the restriction of slit width, the SNR of onboard slit-based pushbroom imaging spectrometers with high spatial resolution is difficult to make a breakthrough. In order to achieve higher SNR, Hadamard transform imaging spectroscopy is used to design the imaging spectrometer with high spatial resolution by replacing the slit with coding mask while its concept will be introduced in this paper. The SNR performance of coding imaging spectrometer used this technology will be simulated with main specifications which include orbital height of 500km, spatial resolution of 1m and spectral resolution of 5nm. As a result of the simulation, its SNR performance is 5 times superior than slit-based design in the same specifications. Moreover, other advantages of using coding imaging spectroscopy will be introduced in this paper. In addition to solve the problem that lights from other orders can’t be excluded when we use grating elements, Fery prisms are introduced to the Offner relay system to design the imaging spectrometer. The result shows that the imaging quality is close to the diffraction limit, and the prisms’ dispersive nonlinearity come out to be well corrected. So coding imaging spectroscopy turns out to be a good solution for high spatial resolution design with high SNR.