Stray light resulting from grating multistage diffraction influences the imaging quality of the spatial heterodyne Raman spectrometer (SHRS). In this study, the stray light was analyzed and controlled to enhance the precision of the SHRS. The optical transmission theory was employed to study the stray light produced by grating multistage diffraction in the SHRS using the ASAP software; a stray light controlling structure was designed in -2.5°-2.5° field-of-view via baffling, beam stopping, and light trapping. The results indicate that the stray light ratio of multistage diffraction is reduced from 4.996×10 -3 to 1.57×10 -8. Thus, the developed structure can efficiently control the stray light from grating multistage diffraction and improve the imaging quality of the SHRS.