As a novel imaging spectrometry, computational imaging spectrometry (CIS) has the advantages of high throughput, snapshot imaging etc. However, there is little research on imaging quality evaluation of CIS system. In the present paper, a quantitive evaluation method for imaging quality of CIS system was presented. ISO 12233 chart was used as the objective source, and then imaging and reconstruction of the spatial-spectral information was provided. Calculating modulation transfer functions (MTFs) for the reconstructed images was considered as the criterion of the imaging quality evaluation of CIS system. The result shows that MTFs for single-frame sampling decrease rapidly with the aliasing spectral number increasing. When the number of the aliasing spectra is 9, MTF for the reconstructed image decreases by 50% compared to the original scene. This work helps better understand the pros and cons of CIS system and arrange the aliasing spectral number reasonably to reconstruct the object scene precisely.