To improve system resolution and image quality,the characteristics of echelle grating spectrography were introduced and a method of fixing and checking for the optical system of the echelle spectrograph was researched.Proposed method could reach the precision of the design through fixing the slot, collimation lens, prism, echelle grating and focusing lens.A special fixing method for the echelle grating spectrography during the fixing process was also introduced. Finally, a calculation formula was deduced based on Reyleigh principle to check the resolution of the echelle grating spectrography. The checked result shows that the resolution of the echelle grating spectrography meet the system requerement of 10 000.These results reported here mean that propose method can offer a reference for fixing and adjusting of other precision instruments.