With the novel spectrum imaging technology development in recent years, the push-broom coded-aperture spectral imaging (PCASI) shows the advantages of high throughput, high SNR, high stability etc. This coded-aperture spectral imaging utilizes fixed-code templates and push-broom mode, which can realize high-precision reconstruction of spatial and spectral information. But during optical lens designing, manufacturing and debugging, there inevitably exist some minor coma errors. Even minor coma errors can reduce image quality. In this paper, we simulate the system optical coma error which influences the quality of reconstructed image, analyze the variantion of the coded aperture in different optical coma effect, and then propose an accurate curve for image quality and optic coma quality in 255× 255 coded template, which provides important references for the design and development of push-broom coded-aperture spectrometer.