In the Sagnac static imaging spectroscopy,there would be impact on the spectral resolution of the spectrometer caused by counter rotating of the Sagnac prism,and even the fake spectrum would be brought in. In order to improve the spectral resolution of the spectrometer and remove the fake spectrum,the relationship between the counter rotating angle brought in when balsaming of the two semi-pentagonal prisms and the shearing displacement caused by which is deduced,the effect on spectral resolution caused by counter rotating error is analyzed,the correction method to the error using Forman convolution is discussed. The experiment was carried out using hydrogen lamp,the result shows that,the spectral resolution of the spectrum reconstructed after correction can be improved and the fake spectrum can be restrained dramatically,the correction result is good.